I know sharing nighttime feedings works for a lot of parents, and I'm not against formula. But I love nursing our children. And I've been very happy with not "revers[ing] the infuriatingly lopsided dynamic" but embracing asymmetry and gains from trade.
It's easier to be pregnant/nursing/etc if you don't think of marriage as essentially symmetrical, until biology breaks that promise. The Vanaukens saw symmetry as so fundamental to their marriage, that they resolved not to have children, who would compromise their equality.