You could argue that "they don't need to" and I call bullshit. Go down to the nearest college and pay attention to the comments made about the female grad students who do eschew the preening hour vs the comments about those who don't. It is absurd. A man who doesn't bother to do his hair right is "eccentric" or "a bit of a slob" but this trangression is quickly overlooked (a fact many geeks take great advantage of). A woman doing the same will forever be looked down on as 'that frumpy chick' or 'she could really be something if she took care of herself'. Do you see the difference in how the value judgement plays out?