This topic has been done to death in the past, and if you use the search function, you can find all the information already posted.
But for those who cannot seach, here goes. Again. I used to believe what Rachel wrote, too. But that changed as I learned more about the different roles which define the sexes, especially when it comes to sexual attraction, and social responsibility in humanity's past.
Very, very few people have any idea of what turns them on; most just term it 'chemistry', and leave it at that. When you study it, though, it all becomes pretty clear. We are, more than we'd like to admit, strongly influenced by our genetics; and evolution has 'pushed' us to become what we are today. Historically, women are attracted to strong, dominant, alpha male types; and even those who have learned the down side to being attracted to a male who is more likely to stray, are still attracted to him. Those who cannot 'capture' the top dog will often satisfy herself with having a male who displays at least some of those dominant characteristics, even if they're only demonstrated on her!
Feminine traits in a male were always suspect; femininity was (and is) strongly associated consciously or subconsciously, with submissiveness and weakness when compared to stereotypical male behavior. Males were primarily responsible for protecting both the female mate and the rest of the society he lived in, and that is still the case today. Any visible signs that he may be 'lacking' in maleness decreases his attractiveness to the very vast majority of females, whether they are able to take care of themselves or not. It's not a choice; it's just something they 'feel', and if there's anything we've learned, women usually follow their feelings even when all other logic says not to (witness all the women who are physically struck by their mates, but don't leave them; it's an astounding percentage). And, the same applies to displaying any femininity to the males in the society; it makes them question his ability to be responsible for his duty to defend (to the death, if necessary), and fight beside, the rest of the men.
And that is why so much of the world feels uncomfortable with crossdressers. It's not going to change any time soon. There may exist enclaves of 'enlightened' folks where we can exist in peace, but most of the 'plain' folks don't want us anywhere near them.