And this is unfair, and also a reason to be less inclined to have children, and so whenever you're called upon to change things, to make things better, easier, and happier for mothers, you do it, right?

Except that's not the way I see you pulling. I see you giving society a pass on that, and instead wanting it to be more accepting of childlessness.

Being more accepting of childlessness is fine, as far as it goes. Shame is a really bad reason to have children. But acceptance doesn't go very far. If we structure society to make raising children arduous, it's a broken, unsustainable society. (If we structure society such that everyone has piles of children, it's also a broken, unsustainable society. In the long run, you have to be roughly at replacement value, and tweak things back and forth if you get too far out of bounds.)

So, deal to all the women and men who don't want children: we live in a society! Different people can do different things. If you don't want to have kids, no worries! Lots of other important things to do. But you'd better pull with the rest of us in helping kids develop into highly functional adults who will go on to have their own kids and so on.