Yes, I also believe not every woman weighs everything in a way as rational as you do.

That's fine. There's no requirement that you weigh things rationally. I just don't want to give people incentives to weigh things irrationally. I'm not suggesting that if people have children they can't afford to feed, we should arrange things so that the children starve. I am saying that if people have children, that requires certain sacrifices. Many people have children for bad reasons, and then they wind up making sacrifices they possibly shouldn't have made -- men and women both.
I'm seeing the side of the employer here. You can see unequal wages even today where these things are supposed to be more "regulated" in that concern.
I don't really have any problem with that, at least in the case of non-government employees. If employers can pay women less for the same work, they'll prefer to hire women over men. Men will have to reduce their wages to stay competitive. My grandfather was a labor leader in a tool and die union in the South. He was instrumental in getting the union to allow blacks to join at a time when that was almost unheard of. His basic argument to other white labor leaders was this -- if the company can pay a black man less than you for the same work, who's he going to hire when he needs more workers and who's he going to fire when he has too many?
Being willing to work for less money is a huge advantage when it comes to trying to get a job. Government does people no favors when it takes their competitive advantages away. "Equal pay for equal work" is basically just a way to restrict competition over wages.