Well it started out with "Children of the Atom" which was an X-Men fighting game made by capcom, it only made sense to throw their big franchise game Street Fighter in the mix for X-Men vs Street Fighter, then Marvel vs Street Fighter, then Marvel vs Capcom. Seemed like a natural progression.
The problem with MVCI is it looks absolutely ugly. They did a terrible job with the look of the game. I hear the gameplay is good if you are into these games tho. Personally I've never been a big fan of the franchise as it is too chaotic with too much shit on the screen.