Women, in my experience, do not tend to enjoy the intricacies of a rule set. Hell, most female gamers I gamed with barely bothered to learn the rules in the books at all. When a rule set is intricate, and part of the fun of game is supposed to be optimizing your character by understanding the rules, you have already lost most women. Making a D&D character (from AD&D on) has always been a bit like doing your taxes, but currently its like doing your taxes if you're self-employed, work at home, have investments, and claim lots of deductions. I don't find it fun, and I've watched the looks of confusion and discomfort while the third edition character creation rules were explained to women.
D&D RAW combat is also off-putting. I didn't say combat, I said D&D combat. In my experience, women like to pretend to kill things just as much as men. And generally they like their characters to look sexy doing it! They don't so much like pushing miniatures around a table, or calculating which attack bonuses stack.