In short a lot of this comes down to the distinctions between sex, gender, and sexual orientation. Over the past two decades attitudes have shifted to where most people can clearly distinguish sexual orientation from sex and gender, but society still has a way to go in figuring out how gender differs from biological sex. The distinction between these two does not affect the majority of individuals, however, which is probably why most people do not care to distinguish the two.
I don't think that being a so-called metrosexual has anything to do with gender identity. There are probably a lot of metrosexual men that don't self-identify with femininity any more than the average man.
As far as divorcing biological sex and gender - well a lot of guys insult each other by calling each other women for whatever reason. There is no allusions to being gay, and apparently a man can be a "woman" even though his sex is a man. But somehow this doesn't seem very constructive or inclusive.
I didn't mean to imply that the term metrosexual is strictly related to gender. I know that terms like this, as well as behavior about calling someone by the opposite sex or gender as an insult are things that differ a lot by culture and circumstance. I personally don't like it; in high school I was once (or more? I can't remember) labeled a "bitch" as an insult (incidentally I am male sex but prefer to identify as neutrois or genderqueer as my gender identity).
My point is that precisely because society tends to use these terms as insults, and because there is no approach common to society, we have a lot of work to go in revising our approach to views of gender identity, sexuality, masculinity, and femininity in society.
