Do you think most men want to go sit in an office all day doing menial tasks to support their family? Since office work is fairly split evenly by gender, do you think men want to go work on oil rig or construction site all day to support their families?
And judging by the fact that women have rushed into the work force while men have not rushed home, I do think it's fair to say that people would rather be sitting in an office than chasing a toddler around the house.
And because some folks have kids first, then find out how horrible it is. The first child doesn't always seem horrible, so they have another.
And because even happy parents find a lot of the work involved absolutely horrible. I'm not sure if anyone gets joy out of waking in the middle of the night to feed the baby, change an overflowing diaper of shit, and/or deal with spit up and so on. Older children keep doing pretty disgusting things for years to come.
Even jobs taking care of folks are considered low-rung, crappy jobs with horrible pay.
Parenting thoughts from a non-parent - pass.
Edit: Besides, me being childless is exactly why I'm qualified to answer part of this question. I understood that, for most of my life, I had to hope that the birth control methods available to me didn't fail (basically condoms, since I can't tolerate hormonal birth control and couldn't afford to be sterilized, if I could even find a doctor).
Its equivalent to taking relationship advice from the neckbeard down in his mother's basement.
I certainly had no problem warming up refrigerated breast milk at odd hours of the night for all three of my children.
I think everyone should pump and freeze. At the very least you'll be more comfortable. The bonus is that you can make your significant other feed the kid!
We can conclude from these observations that the traditional female gender role isn't all that great, and that there is a lot of value in technology (for now, formula, but soon, artificial wombs) that reduce the need for anyone to do that work.
[1] There is an increased push for paternity leave because dads want to spend more time with their newborns, which is different from wanting to embrace traditional female duties. And a huge part of that push is to set the stage for women to escape their traditional gender role. Dad being more involved from the beginning means that, in the long term, it will be easier for dad and mom to share child-rearing duties. It's harder to do that when, e.g. the child reflexively runs to mom any time it needs something.
Obviously, before anyone makes that sacrifice, it makes a lot of sense to study whether it has any corresponding benefits.