Usually this sort of thing -- a lack of active female characters -- would bother me, but it doesn't in SPN, and I wanted to figure out why. (Although for all I know, really it's all just "mmm, eyer candy" and the rest is icing.)

I think that for me it helps that although both Mary and Jess are symbols, I read them as active rather than passive -- Mary actually does act within the canon of the show, and Jess might as well. And I can't shake the feeling that they were killed off in order to prevent them from taking action. And I see a distinction between them being disempowered by the show and murdered by the demon.

I don't really understand when people say that the women are all evil or victims (except jokingly, which I've kind of done) -- because there are plenty of female characters who are neither, just as there are plenty of male characters who are victims or evil.