I played MVC3 for fighting and rating against my friends, I could care less about music, story, endings,
Heck, this a fighting game, we dont even need that kind of content, let that for other genres
The thing is, Capcom proved that they could make a good story with SFIV. With MvC3, they just pretended like it never even happened. If they're even going to bother putting a story in there at all, which is the reason the game was subtitled 'Fate of Two Worlds', don't you think they should put some effort into it?
With the music, you hear a characters theme every time that character comes out on screen. For me, most of the music ranged from 'meh' to 'horrible'. I found that those particular tracks detracted from my enjoyment of the game, because I really had no option to avoid them. Capcom has proved time and time again that they can make good music for their games, and then we get Capcom's music being 'barely passable' to Marvel's being largely 'ok'.
The gameplay mechanics were rock solid, I'm not going to argue that, but everything else, from the presentation to the characters, just felt lackluster.