MvC3 and MvCI are very different games. A lot of MvC3 involved OHKOing a character once you got a solid hit on them, while in MvCI, the game is forcing you to go for multiple hits and resets due to high (Blazblue esque) scaling on supers and combos, as well as low-health damage scaling.
Getting the first hit is important in every fighting game. MVC games generally put a big emphasis on landing a combo and doing big damage.
This game is similar but the damage is overall reduced so you don't lose a character off of 1 combo, it usually takes 2-3 combos now.
Plus you have combo breakers now too. It's going to take multiple hits to bring a team down in this game. That said these games are always about the neutral first and foremost. You have to be extremely mobile and cognizant of where you are in relation to your opponent and be making fast decisions on the fly. This is the part that is more important to level up in this game over learning optimum combos because even a basic double relaunch combo will do half life but if you spend all your time in training mode learning that 60% combo yet can't land a hit because your neutral sucks... well you are going to be in trouble with the game.
So overall the game is less touch of deathy. That's great. I did notice the difference in damage scaling when I played at my cousin's house last night. I'll dig into training mode once I get it on my way home and see what's up.