Context and general impressions
And then it sort of didn't. There were some episodes with great ideas. The handling of Pike's past and future links to TOS episodes was good, with some subtlety and delicacy in not fucking up the canon, while still adding some new detail that enriched the character. The episode "An Obol For Charon" felt like the broad, challenging stories TOS tried to tell, but with the budget and special effects to make it look adequately epic. "Saints of Imperfection" felt totally new and different, but seemed interesting and exciting. They were doing some real exploring again! No more Klingon War!
And then the second half of season 2 just slumped, mostly. Exploration and discovery were sidelined for timetravellers exposition. If Doctor Who and Back to the Future teach us anything about telling time travel stories, it's that you explain the setup quickly, early, and simply. If you're spending half your dialogue just spelling out what may or may not happen, and then most of that turns out to be irrelevant anyway, then you've maybe wasted my time. I can enjoy long discussions of made-up physics, but I have my limits.
I'm not going to repeat my mistake from a decade ago and write everything off from this point onwards. I'm sure we'll still get decent episodes in future. Disco may thrive in the far future, especially if they keep their better writers on, and leave them to do their jobs unimpeded. And I'm at least happy we'll get to see more Picard later too. But I won't feel fully comfortable until I know Kurtzman has dropped the reins and isn't going to fuck up more things.
Root causes
The explanation for why season 2 went the way it did probably won't be made clear until insiders start giving their perspectives, probably years or even decades from now. But it seems to me that the main cause was likely the change of showrunners a third of the way through the season. That's when the focus of the stories seems to shift towards time travel, but also when they seem to change course on some already established facts. In hindsight, it looks like a lot of ideas were summarily chucked and replaced by the new management, without too much consideration for overall narrative integrity. I'm told this is pretty common with management changes.
My initial impression is that Kurtzman may have been a little obsessed with "fixing" canon issues, in the sense of pleasing older fans who didn't like changes to the way things used to be. On the one hand, I don't think Kurtzman succeeded at that. On the other, I think it was mostly a mistake to try, and I'm compelled to digress a little to explain that:
Don't fix canon that ain't broke
Disco season 1 didn't break the canon. Fans who said otherwise were, at best, premature. The single biggest canon concern, to me, was how they'd handle the spore drive, which was just so extremely advanced compared with everything else until around Voyager, and so conspicuously absent in everything else. Its existence should make a huge practical, narrative difference. Voyager would have been home in minutes with such a drive, the Bajoran wormhole would have been irrelevant, and all the TOS/TAS conflicts over dilithium would have been moot. But I still didn't consider that a dealbreaker; it was just an interesting opportunity to write in the explanation for why the technology was ultimately a failure. If it was so bad that a century later, nobody would even consider using it, then there's got to be an exciting story about why that is, right?
What others have instead chosen to focus on doesn't usually make much sense to me. Bernd Schneider, of Ex Astris Scientia, has seemingly become obsessed with looks, more than anything else. This is silly. His explicit argument is that visual continuity is important, but that's a very 20th century anomaly. Before film, that was never true in storytelling, going back millennia to the first oral traditions. Images always changed, whether because the storyteller said that they did, or because a different artist drew them differently, or because the production design on stage naturally varies from performance to performance. And in reality, this is true of TV series too; entire actors get replaced in roles, sometimes, on the assumption that the audience can suspend disbelief and play along. The fact that things do still look exactly the same when you go back to reruns (which they couldn't if you watched a repeat performance of a play, for example) only helps to reinforce the illusion of visual continuity. Schneider pretends a little too hard, and so can't accept an inevitable change when it comes. The Klingons have never been visually consistent, just as elves and giants in fantasy have always had varying appearances over the centuries. It doesn't change their narrative function. And ships and technology look different too. That's inevitable. I remember laughing, years ago, when I first saw the ship's computer giving paper printouts in The Cage. Things change, visually, because they were never, ever real to begin with. This doesn't alter the story being told.
(I'm not certain, but it's possible the 21st century will change visual storytelling in a different way, because you'll now always be able to pull up an endless archive of images from the past, while watching the latest stuff, and compare them in real time. We'll have to learn how to navigate this option, making it something constructive and fun, rather than limiting and dogmatic. I feel Schneider's approach is more like the latter.)
So I wasn't bugged by canon concerns after seeing season 1, and I struggle to take seriously those who were concerned to extreme, panicked levels. I don't think Disco season 1's complications were necessarily all good, worthwhile ideas, but there was still plenty of room to steer back on course, and it looked like things were being set up that way. Discovery was the only ship fitted with a spore drive, and had already encountered serious medical, psychological, and reality-altering side effects from its use. The harm done to the miniature giant space tardigrade seemed a very clear indicator that they were going to say the technology was more harmful than helpful, and when season 2's "Saints of Imperfection" showed us an entire extra-dimensional ecosystem at risk from it, I thought that was precisely where they were taking this story arc. Given our modern need to urgently end the use of fossil fuels, that felt like an excellent analogy to draw, very much in line with the old TNG style of scifi parable.
But then Disco season 2 didn't end up satisfactorily addressing the spore drive problem after all.
The following is just a list, in no especially clear order, of all the things I object to in Disco season 2. Some have already been pointed out by others. It turns out, the majority of my complaints center on the final two-parter, "Such Sweet Sorrow", though a few problems have earlier roots than that.
* Dr Gabrielle Burnham's body was found by Leland, and Michael heard her die. So how can she also have survived to become a time traveller? It's possible Leland was lying and Michael mistaken, but the show makes no effort to clarify this. It just looks like a plot hole.
* What were Control's motives anyway? It appears on screen, via Leland, to monologue its evil plan directly to us, and I'm still not sure. Kill all life, yes, but why? I don't like a vague villain, I want motive and depth.
* Why set up that spore drive is bad for mycellial network natives, then ignore that huge threat? It seems that after the change of show runners, not only does the Discovery keep harming the jahSepp's ecosystem with more jumps, never once showing concern for the mycellial plane, but they also waste the story potential to show voluntary abandonment of dodgy tech for environmental reasons.
* Similarly, whose dumb idea was it to have Discovery & Enterprise disgorge literally hundreds of shuttles to act as fighters? Star Trek shuttles are just space buses, usually unarmed, and it's long been established that even the huge Galaxy class doesn't carry hundreds and hundreds of them. Now, if there had been a good narrative or artistic purpose for it, I might have accepted it. But instead, they just mention it, very briefly illustrated with an unreasonably large swarm of them, and then the rest of the episode proceeds with their vast numbers being totally irrelevant to anything.
If anything, I feel it would have been more dramatic if only a dozen or so had been available, few enough that we could have shown the pilot of each as a real character, not a distant video game icon, with tensions rising as each unlucky one is killed in the battle. My first instinct was to dismiss the whole shuttle-fighter concept as lazily stealing from the fighter scenes of Star Wars and BSG, but I now realise that the more character-driven scene I've just suggested is actually closer to watching Luke or Starbuck struggle through in their lonely little cockpit. So I guess "Such Sweet Sorrow, part 2" didn't really plagiarise, it was originally stupid. People used to mock Voyager for maybe having one or two shuttlecraft more than it ought to be able to fit inside. I would love to go back in time and show them this new thing, to put their complaints about Voyager into perspective.
But never mind that. Let's take it as given that there are these 7000 vessels of one sort or another, and yet none can help Discovery in any way at all? Sure, they make the excuse that communications are limited for security reasons, but they work around that limit fine when they want Enterprise and Sarek and Amanda to pop by. So is there a limit or not? Is there a workaround to the limit or not? Maybe some of the 7000 starships are too far to get there in time, but none of them can make it at all? No major starships are faster than a little Vulcan diplomatic shuttle? And only Enterprise can help? It seems a silly gaff by the writers, and I think fixing this might have saved them the trouble of feeling they needed to cram hundreds of anonymous extra shuttles into the end boss battle. Just two or three additional starships, rushing to be the cavalry, could have added some decent extra tension, evening out the battle numbers to something slightly more realistic, and they could even have shown us quick glimpses of their non-human captains, for a little bonus variety.
* The idea that the season had to be resolved with a big battle seems terrible to me. It's just too video gamey. Even season 1, the "war" season, cleverly wrote itself out of that mess with some internal Klingon diplomacy, sidestepping a big, dumb battle to the death. It wasn't a flawless ending, but it shouldn't have been that, or Kirk wouldn't still face trouble from the Klingons a decade later. So given that, it was a damn clever path out that the season 1 writers found. But the season 2 ending was just "shoot everything until we can magically escape"; I feel this was uninspired, and a bit un-Trek.
* Forcing in guest cameos as fighter pilots was weird. Saru's sister, Siranna, was a rural, pacifist priest, and then suddenly she's recast as a generic Star Wars fighter pilot character, pew pew pew. It made more sense for Queen Po to be present already, as she was engineering shit, her established major talent; making her then also have to be yet another fighter pilot was weird. It made good enough sense for the Klingons to arrive as the cavalry in the end, with full-size starships, and it probably would have been much cleaner, clearer writing if it was just a way to show the two recent war-enemies suddenly working together towards a common goal. Trying to make the Xaheans and Kelpiens fit in there too muddies that nice, simple demonstration of cooperation, not least because they were then forgotten for the rest of the final episode anyway. There was no advantage to including them, it was just weird.
(Although, why did Control stay neatly inside Starfleet computers only? If there was free communications with Klingon and other alien receivers, why didn't it copy itself onto their computers?)
(I also think it would be nice to see who the Ba'ul really are. There was a Wizard of Oz analogy waiting to be grabbed there, once we saw a little of the Ba'ul behind the curtain, but the show never progresses them much beyond mysterious semi-magic demons.)
How come they had drones for repairing the outside of the hull under extreme conditions, but none to just pull down the door-closing lever for Cornwall? How come all those clever Starfleet brains, who built a new time-jumping suit in record time, couldn't improvise a lever-pulling gizmo to close the door without needing to kill anyone? I mean, I could have rigged that for them with just a length of sturdy string...
* The Red Angel suit was ridiculous, once revealed. It wasn't super-science, of the sort we just have to accept in Trek (like transporters and warp drive, and even spore drive). It was just magic. It can fly better than a full starship, it's ridiculously survivable, it never runs out of power, once started up, and its computer memory is far more vast than Discovery's. And it can do all sorts of plot-convenient combat and medical things too, literally raising the dead! And this is early 23rd century Federation technology? Nonsense. It is level 9 magic.
* What were the first seven red signals that the season started with? They definitely were not the seven that Burnham later retroactively creates at the scene of each episode, because those episodes all happened after the season had begun. And the original seven signals all appeared before Pike arrives to take control of Discovery. The first one they visit is described as having lingered when the other 6 vanished, so there's 1 that's possibly justified, unless Burnham's signal there was just appended to the lingering 7th. But then there are 6 signals Starfleet definitely received weeks or months before Discovery spots 4 further signals that lead them places, adds 1 more shortly after, and 1 that is somehow sent back in time to signal to Spock, many months later. So in fact, there were 13 or 14 signals, and we still have no idea at all where the first 6 or 7 came from or why. Is it even worth asking for a rational explanation? Clearly, if one was written, we're not being given it.