Yeesh, for a bunch of proto-feminists ya'll sure be missing da' point. Which is... Mary is the incarnation of the female, of the goddess, without which Christianity would not have been able to grow into a world-wide, almost beyond time cancer institution.
People respond to the sacred feminine, to that idea of miracle of birth, of regeneration, of renewal, and Mary is the incorporation of that into Christianity. Christianity was most excellent at taking the holidays, rituals, believes and symbols of other cults and superstitions religions, and incorporating them into the larger framework.
That's all old Mary is, just the way the Catholic Church put the feminine into Catholicism.