MVC2 is one of those games where the balance was to me a fluke. Somehow, out of 56 characters available, only maybe 10 are viable at high level competition, and yet there is still a competitive community for it. That is very strange to me. Seriously, the game might as well be called Cable/Magneto/Storm.
But yeah, MvC2, by virtue of having been around of a long long time, also has one of the most ridiculous learning curves ever.
There actually is a lot of strategic decisions that need to be made throughout the match, but it is no where near games like SF2 or some of the 3D fighters out there. And this shows when the MvC2 players try to cross over into other games. i.e. Justin Wong, one of the best MvC2 players out there, can bring a strong performance, but ultimately never top performance in SF3 or SF4. Why? because MvC2 rewards high execution more so than good decision making. A huge part of your strategy hinges on you being able to perform the various infinites, or at least NEAR infinites. The whole game was basically built on combos.