If I make a werewolf on a WoD MU, I'm playing a werewolf. Sure, there may be kinky shenanigans going on, but there might not; who knows?
If I make a werewolf on an Erotic MU, I'm definitely planning on doing kinky things with the shapeshifting and the biting and the grrrr, alpha wolf, grrr.
There's a very clear veneer that colors every intention.
It's the difference between the pizza delivery boy arriving at a sorority house in a PG-13 movie and getting macked on by a few hotties (he gets macked on, but the movie goes on with either his story or the sorority's); and the pizza delivery guy arriving at a sorority house in a porn film and getting into an orgy (the orgy is the movie; that's the point). It doesn't matter if in both stories the pizza delivery guy gets sacrificed to Cthulhu in the end -- the tone and point of the scene/movie is different.