I think most of the criticism for Martial stems not from fans actively having an agenda against him or disliking him, but from pure frustration.
We can't deny that he's 100% amazingly talented. Dribbling, pace, strength and composure in front of goal is what I associate with Martial when he's playing well, and he has good hold up and link up play, and isn't a bad crosser actually. In fact, I would go as far as to say that he's perhaps our most complete attacker.
Which is why it's so unbelievably frustrating to watch him only give 80% when he could give 100%, and with the right attitude he has the ability to destroy defenders when he's on his game.