My guess is it's just common culture right now. If you were to go to a beach wearing a speedo here in the US you'd get a lot of flack for it, especially considering that bulge is genitals while boobs and butt are not. Japan is probably the one place where someone would add a feature like this without a second thought (and even then, they just might not include it because women are more popular, even with women to a degree, because Japan isn't Ancient Rome).
I would wait for a mod like Quto said.