Wearing dresses or trousers is not some kind of innate, genetic requirement of being born female, it is an outcome of a particular form of social history which polices women's bodies.
Dresses were designed to be both modest, so restricting women's sexual expression, and limit their capacity to be active and participate. Women being women, never let that stop them; Freya Stark climbed mountains in skirts.
But there's nothing inherently female in wearing clothing which is one tube instead of two. Other cultures are less interested in gender-coding tubes of fabric. Masai men, for example, traditionally wear bright, red robes to do manly things like hunting lions.
In Western culture, men in dresses are usually taking the piss - frocking up is popular with drunk young men, because it's a daring foray into the forbidden realm of femaleness. But of course, after the naughty thrill, they pull on their trousers in the morning and go back to their privilege.
Men generally don't wear dresses because they like a nice print or enjoy the waft of fresh air around their parts; they wear them either to be a bit shocking (but knowing that their privilege is just a pair of pants away), or because they are performing femininity. For them womanhood is a performance made up of stereotypes; dresses, make-up, hair-flicking, coy gestures and the rest.
If men take to dresses in droves, I don't care - I'm sure many of them would be more comfortable (and at last we'd get clothes with decent pockets). But as it stands, men in dresses are treating the reality of being born a woman as if it were no more complex than a bit of lippy and a sequinned sheath.
Wearing a dress because you like it is one thing, go for it blokes. But wearing a dress because their feeling of being a woman is so restrictive, they can't see past representations of "femininity"? Yeah, fuck off.