No, the real problem is that people on the internet seem to tend towards absurd extremes in one direction or the other, when it's far more likely that the truth is somewhere in the middle.
Nomura's never been a "knows everything that's going to happen from the outset" sort of guy. Anyone who's followed his work on Kingdom Hearts should know that. He operates in concepts and images and snippets of dialogue, and he builds the rest of his games around that.
Ever seen Another Side Another Story?
That's how Nomura operates -- a few strong visual concepts that carry through to the final product (a dark city lit with neon lights, mysterious characters in black cloaks, evolved Heartless, fighting with two Keyblades), a bunch of lines that show up in the final product but not necessarily with the same impact as one might have assumed, and early character concepts that are close to the final product but are still distinctly different (like Kairi in the ending).
As such, there was never any reasonable expectation that Nomura knew exactly what he wanted the game to be at any given point. The expectation was that, like Kingdom Hearts II and Birth by Sleep, he'd be able to build a game around the super-early concepts he revealed that felt consistent with what he'd showed previously.
Why bother rerendering the CG? That's pretty obvious -- Nomura's a perfectionist who was tasked with making marketing materials for his game and took advantage of the budget he'd been granted to make things more to his liking. That has nothing to do with not knowing what he was doing and everything to do with him simply never being satisfied with a final product.
Remember, we're talking about a guy who
made significant story/presentation modifications to a game that had already released (including additions regarding character motivations). Rerendered CG is nothing Nomura fans aren't already familiar with.
Well, even executive-level employees are still subject to the whims of the investors, and it's pretty clear that Disney/Squenix's finance department wanted KH to be a yearly series whether Nomura stayed involved or not. It's not difficult to imagine a situation in which Nomura was given the choice of either working on more KH games or having them done without him, and since he seems to think of the series as his baby... And even if he didn't, he still wouldn't have been able to work on Versus because Squenix's big in-house team was occupied with either XIII or emergency repairs on XIV until 2011.
Well, that mostly comes down to different decisions on the part of marketing -- Nomura was asked to put something together for the FNC presentation when he'd barely even gotten started thinking about Versus, while FFVII held off on showing anything until they actually had a game running.
And, even so, it's ambiguous as to when the kill-em-all thing happened in VII's development, so that could have been after the game had started being shown. =P
It's absolutely the same thing, considering the ridiculous difference in cost between pixel world maps and FFVII's pre-rendered CG backgrounds/3D world map. Actually, the difference in scope for FFVII was probably significantly bigger in that regard.
That's what happens when you try to implement a story in a game. Play the game I linked. Heck, it isn't even unique to games.
Rogue One made sweeping changes in reshoots only months before its release.
And, no, Nomura never said the story was finished. He said the
scenario was finished, which probably referred to something earlier than even a final script.
Again, a lot of this is a matter of marketing being started far, far earlier in the process than it was for FFVII. Other games with early concept trailers -- like, say, KH, as I mentioned earlier -- show similar design changes.
Here's another fun one... remember black-haired Tidus? =D
As I said above, Nomura said that he had a
scenario set, not a script. He just got mistranslated. =/
My guess is that Tabata only finalized the story roughly around the same time as the game was content-complete/"pre-Alpha" back in November of last year, due to the simple fact that the ability to execute a story in a video game depends on the ability to execute the gameplay corresponding to that story. Nomura never had a content-complete/"pre-Alpha" game, and therefore it's perfectly reasonable that he never had a finished story. =P