KH at its core and conception was supposed to be a SE/Disney collaborative project. It worked well with KHI and CoM, and it was passable with KHII. Blaming Disney for the downfall the series has gone in I feel is unfair, since the whole premise has been to visit Disney worlds, and that was the charm and magic of it. Mixed in with some moving character moments, and you had something solid. Take Disney away and you just have another FF but with a madman with no sense at the helm and in control.
The one to blame is the director behind it all.
No one asked for a bloated cast. No one asked for a dozen Soras and Xehanorts running around. No one asked for retcons or random additions that happen just cause it moves the plot where Nomura wants it to be no matter the lack of build up to it, there was no need for time travel, no one asked for multiple SRK rip-off trio shit. All this overly complex stuff and machinations are out of Nomura's head. 358/2 Days was unnecessary, period. Xion was unnecessary. Did we really need Ven? If it had to happen, him and Roxas should have been the same person (hell, that would actually make the whole entire thing better, more so as to where we are now currently...would be glorious). And Aqua was great for being the well-done Kairi, but she was pretty much an observer of the other two driving the plot. Those post-KHII side games are what ruined the direction of the series if you ask me. That's when it had too many characters for no reason other than, what, to keep us busy? Then Nomura completely failed at keeping these plot threads together as they all came to a head when it was something he created. So he went off a check list and missed plenty of intercharacter interactions and growth.
Nobodies are supposed to take after their originals with "slight differences". There was no need to explain Roxas' appearance, especially since he's on the "special Nobody" bracket. There was no need to explain why he left because we had already known why, so why allow Kanemaki to input a Sora replica but not really due to looking like Kairi because memories but has black hair for some unexplainable reason. I remember in an interview he stated it was because he thought it was "cool". That's how this guy's mind works. The rule of cool. Do it now and think of the consequences later.
Oh, there were consequences alright. You got a mess of a narrative.
Organization XIII should have been put in the grave the second KHII ended. Bringing them back does no favors and now he has to consider another set of 13+ villains. It's stupid. Can't forget the KHUx cast that he's really trying to shoehorn in.
There, that's already cutting away more than half the baggage.
Nomura can't keep shit simple, he doesn't let characters rest, and he keeps making stuff up along the way. That's the issue, not Disney or Disney worlds. If anything, I consider them collateral damage left in his wake.
Oh, we can't forget Walmart Noctis and Stella to add to the mix. He couldn't make his dream of Versus XIII be real so he's injecting it into a series that has no place for that. Obviously not over it.