The recent unacceptability of homophobia has pushed into the closet, so to speak, discussion of why (in the United States) metrosexuality is controversial and a big reason the average man dresses so poorly: there is tremendous fear of looking gay.
It is not wholly irrational, either.
Heterosexual men are quick to make negative judgments about sexuality, although they aren't very good at them
Changing roles have increased women's expectations of male sensitivity and male appearance. But there's a lack of evidence that they are now more eager to mate with outwardly feminine men. For some female perspectives, see this article
. It appears that, more than anything, modern female aesthetic tastes demand more positive display of the male body, like moderate muscularity. Even unattractive displays like square-toed shoes are preferred, as at least they are quite male.