I agree that we should improve things through modern medicine, just sharing what I remember/ found about the evolution side:

It's been a while, but from what I remember, menstruation evolved in humans (and closely related species) as a defense mechanism for mothers. Other species reabsorb the lining instead of ejecting it, mainly because it's thin enough to do so.

For one, a thicker lining protects the mother from the baby/placenta, which is trying to embed itself further to better pull resources from the mother's body.

We also have a much higher chance of miscarriages and improper development of the fetus, and so having a thicker lining and a method for "ejecting" allows for the mother's body to remove a fetus that won't make it, instead of burning more resources growing it or risking harm from miscarriages.

When I think of bad evolution, I think of stuff like choking, which only happens because of the order that the two pipes evolved. I don't think there's an evolutionarily helpful reason for why we can choke