I'm not trying to disagree with you, I have a 7 month old son, but what about the joy you felt seeing her being born? I know that isn't a mundane thing and that you likely won't have it but a few more times but there are experiences that children can't have, that are, at least, as transcendent as a child's first taste of chocolate.
But that's precisely the thing. In a stable population, births per year are inversely proportional to life expectancy. So whatever joy seeing a child born brings to people, there will necessarily be less of that per year aggregated over the whole society. A society where everyone lives longer is necessarily one with a smaller proportion of joyful idealistic children and a higher percentage of cynical jaded older people.
