> If having children is so wonderful one must wonder why men still haven’t by large decided to pitch in when it comes to the nuts and bolts of child rearing.

It's, by and large, because those are not the men that women select to have children with. When women consistently choose the man with the six figure salary, but that implies working long hours, what follows is predictable.

There is also a high degree of adverse selection there because a woman can't tell how much a man will help with the children before she has the children, by which point the father is already chosen. So they choose based on what they do know (e.g. salary) which is inversely correlated with that.