Why do female pop stars dress for men?

When men wouldn't be interested in buying their music? Their music is targeted towards young girls but they dress for men, i'm talking about girls like Katy Perry, Miley Cyrus, (insert Disney star here), uh I dunno... Jennifer Lopez, etc... I don't get it. Personally I don't really care because I can't stand that kind of 'music' (if you could call it that) anyway but i've always wondered why they dress the way they do if their fan base is mostly young women... Also, do you think they're sending out a bad message? I heard a Rhianna song (oh there's another one for you) about S&M and I imagined little pre teen girls listening to it and I dunno it grossed me out a little. I see little girls wearing patent leather high heeled boots and tiny skirts and I thank god I grew up in the 90's. Any thoughts?