I think this is a very clever observation!It's true that the majority of artists don't get interested in male superheroes when drawing pinupsbut I think it's in great part because in this society we have, people in the media have always given the message that woman it's beautiful, and men don't. Also, they have objetified female beauty to the point where they give the message the the only thing that worths in a woman it's her body.So that's why the artists (or some of them at least) who actually would like to break down this bad perjudice and draw a male pinup to show men's form is beautiful too; they don't do that cos they don't know how to draw a male pinup, how to make a man sexy, because they are too used too see and hear everywhere stuff that only portraits female beauty.I think it is possible make a good male pinup, one that actually looks sexy and not ridiculous, if one day they stop to think about the beauty of the male body, and if they would, then it would be cool I think