1. I don't believe they changed it because of complaints. I don't recall almost any complaints about this in particular.
2. If they did change it because of complaints, people have the right to complain, and they have the right to change it.
My guess is that it is more likely related to ratings, or to the image they felt the game was projecting, rather than complaints about the butt slap. Like they went after this, even though it is pointless to do so, because it is easier than making a substantial change to the design.
Having said that, people have the right to complain about this apparent change too, and I'm going to. It is misguided. I have problems with Mika's outfit and the CA itself, but I had no problem with the butt slap. If anything, the slap was necessary to put the rest into proper context. Without it, and
especially by seeming to censor it, the tenuous value of the rest of the design is made to seem more, rather than less, exploitative. The slap is effective at expressing personality... the extremity of the revealing outfit, by itself, is not imo. If you "censor" the slap, why have that outfit? And if the slap is vulgar (which I wouldn't have thought before), doesn't the outfit have to be as well?