I quite agree, and I'm female. Personally, I think it would really be better to go back to the legal concept of children as chattel, only with male and female parents recognized equally. Girl children belong to the biological mother, boy children to the biological father, unless the biological and any other parents involved have contracted for a different arrangement, or a court has found a parent to be utterly unfit to have custody of any child (not just less fit than the other parent). You leave a relationship, you take your kid(s) with you, and you have no rights or responsibilities with regard to your ex and his/her children.
My only problem with your proposal is the idea that boys don't need mothers and girls don't need fathers. I think that a presumption of shared custody would be better- there would be less of using children as pawns to hurt your soon-to-be ex-spouse.
Are you single and do you like warm fires in rustic mountain cabins?
8-)_~~