(1) Story Mode sucked ass. It was too easy and vastly inferior to MK9's story mode.
(2) Unoriginality of new characters. Cassie Cage, Jacqui Briggs, Takeda. Seriously? Instead of including much better characters from MK9 (Kabal, Cyrax, Freddie) you invent a bunch of new characters that are just hybrids of the others with basically the same moves. Making them have kids is just oh so lame.
(3) Including too many variations. To me, simplicity is best. Having a bunch of variations makes learning combos/characters/match ups just that much harder and ruins the simplicity of the game and probably tournament play. Why should I should have to learn the same character 3 times? Why not include these extra moves into the same character? (or maybe just two variations instead of 3...)