Sexism does hurt men, and that is one of the ways -- the idea that men have to be muscular and stoic and brave is just the other side of the coin that says women need to be pretty and caring and kind. I wish we lived in a world where it was OK for men and boys to be sensitive and cry and want to be dancers and artists and wear pink frilly clothes. I want that just as much as I want it to be OK for women to shave their heads and be athletes and politicians. I want everyone to be able to pursue whatever it is they want, whatever makes them happy, without concern for whether that class of happiness is supposed to be available to people with their chromosome set.
But even that is missing a very important point about those fit, hard space marines we see so very many of. That body and that man are fundamentally a fantasy about being powerful. You play these characters not because you want to look like that in real life, but because you want to be that badass and strong and capable, to have that much control over your life.