What I find interesting is that aggressive female sexuality is 'acceptable', but aggressive male sexuality is not. Or, to put it another way: it's possible for a female hero to 'go bad', seduce or rape male characters, then 'snap out of it' and return to being a hero; a male character who 'goes bad' and rapes a female character generally becomes a villain forever.

There's a lot of weird double-standards when it comes to sexuality, of which the costume thing is an obvious one. They do swing both ways, though: While the overt sexualisation of female characters reduces them to sex objects and two-dimensional femme fatales, they're very rarely presented as genuinely 'evil'... their promiscuity makes them 'bad girls', but that 'badness' is presented as erotic and alluring. Male characters, by comparison, are almost never permitted to be overtly sexual, and when their sexuality does manifest, it is usually portrayed as threatening and aggressive. Both sexes lose out: Women get the message that they must be sexually aggressive to gain power, but that female sexual power is something that should be rightfully 'tamed' by a man, and men get the message that their sexuality is horrifying and evil. Win-win!

Conclusion: genre fiction tends to treat human sexuality in a very shallow, repetitive and negative manner? The real WTF is that people are still surprised by this. :P