I'm skeptical that they actually cut enough content to make a whole 'nother game. So what, this game was planned to be between 80-100 hours? Sorry, I don't believe that for one minute.
If anything got cut out from the game, it's Square Enix's fault (and perhaps they might've cut it for good reason? nah, of course not, it was the best part of the game!). I don't see any reason to be blaming the 360 here, especially considering how Lost Odyssey went over three discs, this game could've as well.