I don't think I've spoken on this topic before, but the vitriol between the misogynists and the misandronists is particularly caustic this year, at least on Twitter.
Why do men need a(nother) day about themselves? I think we need to consider who we are, and why.
Masculinity is an arbitrary social construct. Biology gave me some physical characteristics, everything else is up to me. Same goes for you.
I like Linux and science fiction. I like weightlifting and mixed martial arts. But I also like playing with my children and watching My Little Pony episode marathons with them. I like gardening and cooking (badly). And I love music, live theater and movies that can make me cry. All of these experiences affect me inside. They make me whole.
I'm just a person getting to know myself, over time. I'm raising my daughters to be people, too. They play with dolls, and do Taekwon-do, and step dance, and write code. I'm exposing them to everything.
They'll have the same freedom we all should allow ourselves: the ability to decide for ourselves exactly who we are.