@medium-density,
We seem to be disagreeing on a couple of things.
1) I don't agree that men paying to see women in bikini's (a voluntary interaction between two consenting adults) has anything to do with sexism. You need to define what you mean by sexism, but this interaction is clearly not unjust in any way.
2) I don't believe that human sexuality is bad. I don't believe that men being "turned on" by seeing a scantily dressed woman is a bad thing (or constitutes "sexism"), nor do I believe that a woman flirting with a man is a bad thing.
I agree with you about how culture informs how we interact. And, there are things in our culture that I still think are sexist. I am very happy working to change things in our society that are unfair or discriminatory. But this isn't one of them.
Our society values freedom. It sounds like you want to dictate how women choose to express themselves. Of course you have the right to critique the culture you are a part of, but there are obviously lots of men and women alike who don't agree with you.
When it comes to human sexuality (as it evolved over millions of years) I am saying something much stronger then "why fight it?". I am saying "why not enjoy it?" within mutually beneficial voluntary interactions between consenting adults. Your assertion that nature should be "faulted" doesn't make sense. Nature should be celebrated for our sexuality.