There are lot of alternatives. Men can be primary parents (I was, once the kids got to about the age of eight or so, and was an equal parent before that) and they could stay at home (I continued working, but I was already self-employed and working from home, and my ex never worked after having children).
I think the ideal set up (it would have been so for me) would have been for both parents to work part time.
Of course it still comes back to, you should be able to raise a family on the equivalent of one full time income.
Of course, if the leisured society predicted a few decades ago had come to pass it would be one part time salary.