I can't speak much about the eroticism of dressing in feminine clothing that a genetic male experiences, but I can speak about what women feel when they wear sexy things.
First, let's make allowances for age. I'm not in my 20s anymore and although I do feel erotic, it is not the same as when I was younger.
But ... allowing for young women who are learning about their sexuality, generally when we wear sexy things it is not the things in themselves (corsets, nylons, panties, racy bras, etc), that do it for us. It is the idea that we "look" sexy enough to appeal to a partner. In other words, a woman will become aroused just like a guy will, her fantasies will run to having sex with a partner, and she will put on the things that would excite him. In her mind, she becomes the woman that HE cannot resist, and she has fantasies or driving him wild with desire.
Men are visual, and they like to look at sexy women when they are aroused. Women know this, and they like to look sexy when THEY feel aroused, in order to attract the men. Yin and yang.
Most women (unless they have a super high libido), will not become aroused just by putting on sexy things, if they're not aroused already.
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As to your question about why fetish CDers are looked down upon, I should think this is only in forums where there are many "identity" crossdressers and transsexuals who are trying to be accepted for who they are and who dislike to be associated with the public's view that crossdressers are fetishistics perverts. We do live in a puritanical society, unfortunately.
If you went to a site strictly for men who dress for sexual pleasure and there were no members who did this to express a feminine identity, I don't think you'd be vilified.