If versus was so good they wouldn't have changed it, but they did.
I could write a long paragraph explaining why they didnt go with Nomuras vision. But it mostly had to do with Square not giving Nomura resources at the time he was making it. Kicking him out cause he was taking too long whilst square was mostly at fault for making his team work on ff13 and 14 instead. Then when Tabata came in Nomuras project was too ambitions so they had to put on a new writer to crunch down and change the story so it would be easier to make cause the deadline for a 2016 release was coming quick. Not so much about versus being bad was the reason that they changed it but that they never let Nomura fully tell the story he was going to tell.
I don't see why he'd hold a grudge when current FFXV has more in common with E3 2013 gameplay wise (even with differences) than Versus XIII, and Nomura was still there during that year with Tabata until December.
The e3 trailer was probably part of Nomuras vision. We hardly saw any Versus stuff at all only stuff from early game in the early days. Yes the e3 trailer resembles stuff from xv. But that because XV does have some concepts from versus. The dissidia writer took the versus story(nojimas script) and streamlined it, condensed it and changed it drastically, but stuff like the Altissia invasion was going to be in Versus as well.
This is new. When did this come about? I didn't know Versus wasn't pleasing the people in the pre-production phase. Maybe those rumors about Nomura holding a grudge are true after all...
Im sure he holds a grudge just like I said in my first response,square never allowed him to finish his game. I bet hes very angry about that.