I think that's my point. I don't think Aladin and Hercules being in the same frame is the meat of the series. Sure, KH got people into the game by seeing, what if Cloud and Tarzan together. But not a single one of us stayed for that. We stayed for "one who knows nothing can understand nothing". We stayed because of Another Side Another Story and Deep Dive. Because while you were fighting Jafar, you were reading about a man performing human experimentation to see what exactly be needed to do to create darkness.
You could certainly have a movie about some Disney characters together. I daresay it might even be financially successful. But I don't think it'd be hugely so, there's been other attempts at that, and they've been... fine. You can't just make Avengers, you do have to properly set that up, or you end up with the failure of DC.
I think maybe I'm explaining myself badly. I don't think you should adapt the cutscenes into the movie. I think you should take the overall beats (from station of awakening to boarding the Gummi Ship) and make a good, exciting, quality movie around that. Add whatever subplots you need to make that happen.
But I maintain that the whole reason KH works as a story is the underlying melancholy and dread, and if your adaptation is happy happy Disney happy, then that's just a new IP wearing KH's face as a mask.
If what you're trying to say is that the original material is what should be focused on Destiny Islands through Traverse Town is still a pretty poor choice. Because the only Ansem that sequence contains is the potato sack one. Sure, you could move finding his reports forward into the story, but that messes up the pacing of how his character is revealed. (Also, the report you get after fighting Jafar is the first one, and it makes no mention of the human experimentation. Ansem being a bad guy was originally a late game twist.)
Saying that the crossover elements aren't part of the meat is a bit weird when we're discussing an adaptation of KH1, which had the Disney parts integrated pretty well into the story. But you know what, sure, just as I can imagine the world choices being swapped out for other movies, I could also imagine them being swapped out for original material that fulfills the same plot functions. And hey, maybe that would make it easier to adapt the story into movie form.
And I can just imagine some writer taking this proposal to a Disney executive for approval. Then the executive stares at the writer and asks why they're trying to take the crossover parts out of the crossover property. Especially when they were already planning to make the Council of Disney Villains into the cornerstone of the movie's advertising. What devoted KH fans consider to be the soul of the series is not going to be the only consideration when making this movie. Like it or not Disney is still a core part of the series identity. Which is why we continue to have Disney worlds even when the plot of the games has nothing to do with them. The best we can ask for is that the worlds are integrated into the plot.
(And just to make it clear, when I suggested three or four Disney worlds I wasn't suggesting only Disney worlds. I assumed that all the original worlds being included went without saying.)
Imagine if when adapting Harry Potter they decided that first book had too much detail to fit into a movie, so they decided to expand the story up to the point of Platform 9 3/4 into a full film. I guess it could be interesting if they got the right writer, maybe a bit Roald Dahl-esque. But anyone remotely familiar with the books would be asking why they decided to hold off on the much more interesting hook of going to magic school.
Destiny Islands through Traverse Town is a good start to a story, but it's just that, a START. Even if you somehow manage to make a watchable full-length film out of it by inserting lots of filler full of melancholy and dread it's not going to be as enticing as the journey and adventure of saving a bunch of Disney worlds.
For the examples above, Persona 3 had a quadrilogy of movies for each act, with each movie’s title making reference to each season in the year-long story.
Persona 3 was an 80-hour game compressed into four movies. So if we keep the same ratio for a 20-hour game, well...
But I gotta admit, I would be willing to forgive a great number of flaws if the KH movie had beautiful 2D animation like the P3 movies. But unfortunately that's not the medium the rumors are saying it's in