Eventually, lower populations will be better for everyone, but the problem is how we get from here (10 odd billion) to there (3 or 4 billion).
Not by trying to encourage further population growth I would suggest.
Realistically speaking, it's going to piss off women with three kids when the workmate sitting opposite them has four kids and takes home a shitload more wonga for doing the same job.
I remember being one of two childless women in a team of 12, and it was always us two that ended up picking up the slack as our colleagues couldn't do overtime due to picking up the kids - of course they still expected an equal share in the team bonus when we won a bid.
A few of them had pretty snotty attitudes about how we should be prepared to make sacrifices for the future generation. It didn't go down well when they were posting gym selfies on FB while I was still in the office (presumably having dropped their kids off at DM's house for a few hours).
It would've pissed me off almightily if they'd all been taking home far more than me in spite of already getting the same amount for doing no overtime, and most of them were significantly better off than me already due to having husbands in well paid professional jobs.