Its one of the basic things about pop music is that guys will want to be the performers and rock stars and a large faction of the female fans will want to "be with" the performers. Its a fundamentally different experience. Its no secret that the pop acts or rock bands with nice haircuts, well groomed and good looking guys will get more exposure, and female fans respond to that kind of thing more. The clothes, costumes, fashion choices have an effect to how a lot of female fans respond. Hair cuts are important for female fans, just think of how many guys with obnoxious over-style hair will have some huge female following. Like all music marketing, having a dance beat and some catchy understandable sing along lyrics help.
Its already been mentioned before, but the progressive rock category fails on many of the metrics that lead to female fans. The bands are fronted by awkward, average to below average or straight up fugly guys, then you have the long song lengths and on top of that the wacky time signature that can't be danced to.