@Karsh - I have also thought about that. It might be just what JamesHenderson1065 said, which really boils down to personal biases. But if there's a more "universal" reason - or maybe the right word is more "intrinsic"? I can't think of the right word... But what I'm trying to say is if there's reasons based more on the works itself - then it's probably a combination of talent and intent.
Talent as in the bad authors would go for the most default stuff. Including making an unimaginative wishfullment fantasy with generic self-inserts.
Intent as in the more serious type would be looking to actually craft a story. Sometimes just to parody tropes. Sometimes explore implications of a premise. Sometimes create interesting characters to play out. They would write about either genders, but female-centered stories don't have to deal with bad authors weighting down the average.