I haven't played MvC2, though I would like to. What I have played is CvSNK2 EO. I have had that game for 3 weeks and I have almost mastered the ins and outs of 2 characters (Zangief and Kyo). Sure, knowing when to use light and medium attacks is really tricky to pick up on at first, but with enough practice, even againt the computer, you figure out which attacks interupt which moves and how to abuse the bloody hell out of roll. I stopped playing after a month because it was too boring for me personally. When I do go back and play I've been trying to master the boss characters.
I've played Soul Calibur for months and I still haven't mastered Mitsurugi. I know all of his easy cheap combos, and how to juggle them, and when to parry and when to side step, but every opponent is very different and it takes a very long time to learn what each character can do when faced with each different character. You could not handle Ivy the same way that you would handle Taki, nor Maxi, nor Astaroth, nor Hwarang, nor Seung Mina (Is that right?). Mashing buttons against a long range opponent is suicide the fast majority of the time whereas it tends to pay off (too often for comfort) against close range players who can't get their juggle combos started.
So you can say the game is great and easy, and beat Sulik a thousand times on every difficulty, but going up against Cervantes might frustrate you to death because he has a completely different style of play. Going up against a decent Ivy player might drive you nuts because she'll keep throwing you away and hitting you with ranged attacks.
The game is easy against the computer, not against other players. Rolling hopping side stepping and parrying aren't necessarily the hardest parts of the game to learn but timing is everything and if your opponent has a better dynamic of each character vs. character scenario he will beat you (even knowing at what height characters strike their weapons, so that you can block certain attacks with vertical and horizontal strikes that actually knock their weapon away). There is more to Soul Calibur 2 than you are giving it credit for.