While I find people who finds any kind of pleasure from these games (or any kind of rape-hentai) sick, I am against banning and censoring. Ban all you want, the problem is still there: people who actually enjoy this stuff.
And who knows, maybe some people wouldn't do these things in real life if they could do it in a simulator. Or they would do it anyway, I don't know...I would need some kind of study to have an opinion in that case.
About the comparison between rape and killing in games, there isn't that many violent games with the goal to get players turned on by shooting people. Also, there aren't many victims in violent games that discovers that they actually likes getting killed and begs for more...