So, first of all, sorry to hear about your arms. I hope they get better. And since you haven't played ReMIND, I'll try not to spoil anything, though I will say that it DOES clarify some story elements in the main game.
Alright, so let me hit these points in order:
1. So, regarding the new 7 Princesses of Heart. I do somewhat agree with you that they were underutilized. But, at the same time, they were never supposed to have the same role or prominence they did in KH1. The PoH in KH1 were integral to the villains' plans of opening the Final Keyhole and the Door to Darkness. But they made it clear since DDD that the PoH were only contingencies for Xehanort's plan. The fact that they didn't have a larger role doesn't mean they were irrelevant to the story. I'm sure they're introducing them now so they can build up to something bigger later.
2. Honestly, the whole Subject X thing, while totally hamfisted and awkwardly shoved in, was to me no more hamfisted than the way KH1 introduced Ansem as the main antagonist. I mean, you have Maleficent as the de facto antagonist for the whole game, and then at the last minute, out of nowhere, this guy rolls up and is all like, "ok, so, hey, how ya doin', btw I'm the final boss now." Yes, there was lore and background information on him, but there was almost no introduction to him as a character, no buildup—so, again, these problems ain't new.
3. I'm not sure I agree that the space for the worlds was underused either. I mean, exploration is the thing I love most about the KH series, and I know I got that in droves with this game. There were mini-games, treasure chests, and hidden side quests aplenty in each world, even Arrendelle (which, yes, sucked). Only exception is Hundred Acre Wood.
4. I will agree with you that 3 lacked the grand narrative pacing that 2 had. Which is not to say that 2's story was done better per se, but yes, 3 did lack a clear defined midpoint. But then, so did KH1 when you think about it. And I don't really consider the second visit to Traverse Town a definitive midpoint, certainly not the way Hollow Bastion was in KH2.
5. Now, on the issue of time travel. I know this is a controversial point among the fans, because it IS such an overused trope in science fiction, and we're all supposed to groan in agony whenever it rears its ugly head. But, if I'm being honest, I was never bothered by the introduction of time travel in this series. In fact, it felt kind of natural, actually. I mean, lord knows I would have preferred it be explained better in DDD and 3, but the idea itself is one I actually find intriguing, especially with the mechanics that they use. I like the idea of traveling back into past versions of yourself, because that connects organically with the concepts of identity and memories that form core facets of the heart as touched on earlier in the series. And besides, the series has ALWAYS been a clusterf**k of mishmashed tropes and ideas, so why not time travel? Frankly, I think it gets more flak than it deserves. At least this series is original about how they utilize it.
6. I COMPLETELY AGREE on the heavy dependence of Union X. Not even an argument with you on this one. Union X is probably the only game in the franchise I legitimately hate (I didn't even really hate Coded, but I hate this game), and I am getting sick of how prominent they're making it.
7. As for the Disney worlds, I again contest that they had better tension and buildup in KH2 than 3. Again, the worlds in 3 had more direct bearing on the buildup to the final battle. 2's worlds were mostly just pitstops toward the endgame with the same copy-and-paste blanket excuse for why you visit them—there was nothing unique about any of the worlds that helped actually drive the main plot forward. But 3's worlds actually contributed to the climax. Monstropolis basically gave us the reason for Vanitas' recompletion into his own entity again; Toy Box both gave Xehanort the information he needed to begin work on the replicas for his other vessels; Corona and Arrendelle were both the locations of 3 of the new 7 hearts that Xehanort would have targeted if the Guardians failed to play into his plans; and The Caribbean and Olympus both introduced the Box as a plot device, which, though it admittedly didn't come into play in this game, is nonetheless very important to the story going forward. Probably Hundred Acre Wood and San Fransokyo were the only irrelevant or redundant worlds to visit, though even they had more purpose towards the end of the story than most of the worlds in KH2 did.
I think 2 definitely did some things better than 3, of course. I'm not trying to say 3 is just a league ahead of 2. But I do think people are jumping on this ridiculous bandwagon of hating on 3 even though it actually does many things better than previous entries did. Nomura has always been a terrible writer—KH1, CoM, and Days are probably the only exceptions to this (and I'm not sure he actually wrote any of them). But Nomura is special in that, what he lacks in the quality of his writing, he makes up for in how unique, unpredictable, and unapologetically fun it is. And there is value in that, as much as people like to fancy themselves high-brow literary critics for knocking on dialogue and pacing as if these are the only attributes that give a story any weight. And people focus on these problems, which are still not as bad as they were in most of the other games, at the cost of overlooking all the ways in which 3 evolved this series from where it used to be. And I'm just sick of the constant double standard from people who are clearly looking at the past through rose-colored glasses and pretending like things were somehow better. It's just nostalgia—there are some things earlier games did do objectively better than 3, but this concentrated hostility toward 3 is nothing but the effect of excessive nostalgic bias from all that I can tell. A story doesn't have to be great for people to love it—it doesn't even really have to be good. It just has to give you something you don't get anywhere else, something valuable. With Kingdom Hearts, that something is fun, and as long as it continues to be the wacky, unpredictable hodgepodge of a heartfelt story that it's always been, I'll continue to stick around with it.
Alright, I'll follow your lead.
1. I never thought of it that way for the new PoH, if that is the case... I can kinda forgive their lackluster use, I still wish they made them have at least some role other than JUST Xehanort's plan though, hopefully, it's not the last of them, I don't want to see another discarded concept go to waste.
2. I kinda disagree with Ansem being hamfisted in, we were introduced to him secretly at the beginning of the game, and he was supposed to remain a mystery until later, finding out that he was the true antagonist didn't seem like a dumb twist early in the series, because it wasn't overused by that point in the series, Maleficent was a distraction, a puppet to make us not focus on the real threat. Could he have been built up better? Sure, but I still think Ansem is a cool villain, compared to the disappointing MX. Unfortunately, Ansem's uniqueness was ruined by the fact that he is just a piece of Xehanort....really?
3. Sure there were SOME things to do, but not enough to justify the size of the world's exploration, they could have done so much more, but there were barely any side-quests, or anything to do unless you want to talk about Lucky Emblems, and once you do all that, all you got are chests. I loved exploring The Caribbean underwater, that was great.. but still, some stuff to do, but just not enough. (I don't even want to get into how disappointing Twilight Town's size was...)
4. Good to see we are agreeing on some points, let's see the only thing I can think of being a mid-point in KH1... could be either when you lose your Keyblade to Riku, OR when you seal the DtD, when all the new heartless start to spawn. (I agree KHII's mid-point is a lot more clear and defined)
5. Oh boy.. time travel, where to begin with this mess, I'll start off saying, that I don't hate the concept of time travel, I also think it's awesome and interesting if done well, BUT Nomura is using it as a cop-out all he's doing is Reviving the same old characters instead of creating new ones. He's using it as a shortcut instead of solving the problems he's created, even the idea of world lines is fucking awesome, but look how he's using it instead of doing something genuinely interesting with it he's using it to rewrite his mistakes. Also, I'm not saying mistakes as in lore-wise I mean mistakes as in actual writing, the concept is still very new in Kingdom Hearts, but I hope he doesn't continue to do what he's doing with it and actually do something great, and worthwhile. He had some great ideas with it, it's just they were poorly executed or poorly explained, Which is a running gag of this series at this point.
6. ANOTHER point we agree on yay! Yeah, I despise that game, and I played A LOT of it, and none of that grinding was justified for what we got, 100's of pointless missions to get one glimpse of something worth giving a shit about, it was just monotonous and repetitive as hell. And as I already said, it is HEAVILY used for background in KH3 and it's bullshit, I better stop now before I actually get angry about again LOL.
7 Man this a long one.. Have to process this one a little bit... Fact that you could make sense out of all that is insane, I applaud your insight. But joking aside, you make it sound like it's actually digestible, when it was just all over the place the fact that you were able to make those connections is incredible. It's like maybe it had all the building blocks to be a good story but the pacing completely ruined it, maybe it's because of the lack of original worlds? KH 1 and 2 had way more of those and that's where the plot seemed to go forward, but because of the lack of those in 3, it just did not progress as smoothly. You have an interesting outlook on stories, saying they don't have to be good, but just have to be fun... I can somewhat agree with that, but I still think they have to have some basic structure, instead of being off the rails, because why would you want to have a headache, that's not fun, And yeah maybe some of it is nostalgia pandering, but if he would have spent time building-up all these crazy concepts we would have had a much better-polished product. I wish I had your outlook, it might have made it easier for me to forgive all this nonsense.
(sorry for the late reply, not only are my arms messed up but my head is too. I got pretty severe migraines, that I have to take breaks away from the computer, sometimes for several days)