I voted yes. The reason being that some women are coming from abusive relationships and looking for a way to learn self-defense. It doesn't have to be just from abusive relationships, but in any case where men have abused and taken advantage of them to the point that they wouldn't be comfortable working with men on the mat. This allows them the opportunity to being training in a more comfortable environment to them (which is crucial to training). Over some time, I would expect that they would begin to join in with the regular classes, when they're ready.
This is how it was explained to me by my sensei.. and in fact, for a period of time we didn't have a women's class simply because all the women in it were also attending the regular class.
It's for those who need some healing before they can train with men. That's all. And I think depriving them of this great art because they aren't ready to work with men would be a very sad thing indeed.
P.S. Before I was told this reason, I also thought the same... that it was a pointless gender-bias thing. Now I think otherwise.