With a 3-button lay-out here are characters who would have overlapping moves with the TVC form if they go with it...
Strider, Colossus, Jill, Sentinel, Gambit, Tron, Commando, Psylocke, Sim just to name a few...these characters would have difficulty being implemented into the 3-button lay-out without some serious, serious overhaul to their character.
Simply put if they were to put these characters in, they would have to remove attacks out, and simply "choose" the ones that they will put in there for you, which will in turn remove strategical aspects of how they will play and directly change their characters, or completely overhaul their movelist, which again would be literally bs.
Imagine playing Sim and sitting there having to "charge attack" or something, lmao. Look to Strider from MvC1 to MvC2, due to the button map up of 4/2 from 6, Strider automatically loses 2 out of his six options to teleport on the screen and what did that do to situations in which he could no longer use those 6 positions to teleport? However with 3 buttons...hmm...WOW..fail. His Jump on the ledge to cling onto wall gave him multiple options...with 3 buttons...again, Fail.
Yes, 3-button TVC Style Lay-Out was a pathetic move by Capcom, all I know is, I would love to Support Marvel vs Capcom 3, however I will not support this version of a Marvel vs Capcom Game.