What, are you going to adopt?
I've gotten this far in life without wanting offspring for one single second. I think I'm good to go the distance now. There's enough people in the world already. I'll give my replacement ticket to those who actually want to do it.
If we lived healthy and peacefully to, say, a thousand years, you would want kids after a while.
Going on my genetic history, my ticker will explode like a hand grenade within 15-20 years. It wouldn't really be fair on anyone involved to croak before they were ready for it.
If we did live to a thousand years, there's no way unlimited childbirth would be permitted but I'm sure I would get broody at some point in those circumstances.