I think it's a function of the takeover of comics by the fratboy mentality in general. Not that most comic book writers weren't white men back in the 70s and 80s, but they took and interest, or at least felt an obligation, to try to create strong female characters. It wasn't always *great*, but it left a legacy of female characters and stories that even the fratboy takeover couldn't quite erase. But the Ultimate universe was entirely created by them, so no such legacy and thus pretty much entirely useless or evil female characters.