You are right in some ways. For the average person, these games do not (in my opinion) de-sensitize you significantly. I think it makes sense to feel like beating up prostitutes in a video game is bad for mental health stability, but I am against "feel good" solutions if this makes sense.
I also agree that maybe some kids just need to be restricted. However, we are attempting a bureaucratic solution to an individual problem. The problem needs to be fixed within the individual, not with a blanket law on anything.