I don't think lacking Wolverine really is the reason the game wasn't well received. Not that I don't like Wolverine as much as the next guy, but I think there are deeper issues than that.
From purely a fighting game standpoint I would very much agree the game is fine. They actually tried doing something different rather than just dressing up the previous interations with new window dressing, so I give them points for that.
I think the the game suffers from the issues outside the actual game mechanics. I don't think the game, outside of the stages, necessarily looks all that good. And I think the story mode (which has NEVER been Capcoms strong point) is pretty underwhelming especially compared to some of the stuff we're seeing with the DC and Mortal Kombat games. Its hard NOT to compare the marvel and DC games, and when you do storywise at least Infinate doesn't come off looking all that great.