I stand by my statement that it's a cultural thing.
Armed robbery, beatings, killings, torture, etc. are all things that happen in real life. Some of which more frequently then rape. And none of them flare up much of an emotional response from players, if any. We are desensitized to violence. It's everywhere in our games. In our books. In our movies. In our news. In our schools. Everywhere. And it's considered normal.
Someone can make a lengthy RP about some sadistic torture session and, as a player, he probably won't even get any negative feedback at all. On the other hand, someone can make a not-so-descriptive RP about consensual sex and be scorned because "children play this game" and so on. If sexuality can't be addressed at all, how do you expect people to react to rape?
Western society is an ironic mix of hyper-sexualization and hyper-prudeness.
