Of course, the obvious answer as to why that dialogue was never put back in the Director's Cut, is simply that the music crescendos around the original edit. And it having nothing to do with Takei's grievance with Shatner. It would've required rescoring the scene. Clearly James Horner came to the project, and the edits were designed to be "in-time" with his music.
Movies are typically scored after they're edited, not the other way around. Steven Spielberg edited the ending of
E.T. to John Williams' score to make the most of the emotion Williams' music conveyed, but that's the exception, not the rule. James Horner would have scored this scene after it was edited, not before.
I think there are pretty obvious reasons why the lines about Sulu's promotion were cut:
1) It's completely irrelevant to the plot. We never see Sulu take command of a ship at any point in the film, so why bother setting it up? Yeah, it's another way of telling that Kirk is upset that
he isn't captaining a ship, but we knew this already. The movie's already shown us this in about half a dozen different ways by this point. The Sulu dialogue adds nothing.
2) "I'm delighted. Any chance to go aboard the
Enterprise, however briefly, is always an excuse for nostalgia." is a badly written and horribly stilted line, and Takei's delivery doesn't make it sound any better. As has been pointed out here in other BBS threads about this moment, most of the Trek supporting actors were pretty rusty and out of practice by the time the movies rolled around, and at times it showed.
Most of the times deleted scenes are interesting curiosities, nothing more. They're neat to see, but 9 times out of 10, you still say, "Yeah, I can see why that was cut." Any talk about Shatner deliberately sabotaging Sulu's big moment is just George Takei's wounded pride and paranoia talking.
