I'm really on Shat's side when it comes to their TOS/STmovie conflict. Takei always seems to have had a problem with Shat's star character stealing screen-time from his supporting character.
I always got the impression Takei was really hell-bent on his character being 'the captain' and was really sore over that line being deleted from STII. Dude, seriously, get over it.
Sulu is not the main character. Even though he finally got his own ship...
The bottom line is, Shat and Takei got into an ego feud that Takei couldn't possibly win.