I read an article once claiming that the reason women have pushed body acceptance so hard is because they're fundamentally ashamed of their bodies. It made a reasonable argument. They spend 1/4 of their life bleeding from a hole down there. It smells. The rest of the time they're getting white stuff coming out of it or fighting yeast. Plus most vaginas do look terrible. The Internet is full of men talking about how the first time they saw a vagina they were grossed out or comparisons between vaginas and the Predator's face.
Men don't feel inherent shame about our bodies so we never needed a body acceptance movement. The only shame men are now feeling comes from the fact that we are being wiped out of the dating market so now question our self worth because of that.