Yep it's true that maintaining your population is important and I agreed with kal at the time. I'm not sure this is the conscious reason for what we see in child support / general enthusiasm about everyone having kids etc though.
The reason society cares about children is because children are literally its future. Kal was spot on when he pointed to China, they're going to run into massive problems in a generation because they're going to be a nation of spoilt brats who don't want to continue doing the cheap manual labour that made the country "great". Children grow up into adults who then (mostly) contribute back to the society that protected them as they grew.
I don't even have kids (nor want them) and I understand this.
But yeah, let's move on.
LB, you really are a massive geek.