Well that's what you get when you have a male director trying to direct a female centric story while trying to cater to a male audience (and still trying to reel in that female audience).
They didn't want straight male viewers (the audience that mostly watched American Pie movies) to be turned off by this being a story about teenage girls, so they tried not to objectify the male actors (also no matter how you spin it, a straight male director almost always shoots a movie through a straight male gaze). But they also didn't want to objectify the girls too much, since that wouldn't make too much sense for this movie.
So they ended up with a movie about straight girls having sex, without really showing anything, where weirdly enough the movies firmly aimed at a straight male audience (i.e. the other American Pie movies) showed off more (male) skin than this movie.