I simply cannot imagine life any other way than being a parent - there is no way to quantify the magnitude of changes, all for the better, that children bring...
If someone doesn't want children of their own, that's fine.
The only thing that irritates me is when people who have no children or just one child make comments about others having more children.
A few weeks ago, I told the matriarch of my family that I was expecting #4. Instead of being happy with me, she asked if this would be the last one, since children are so expensive now-a-days. It was funny hearing a nearly 90 year old woman asking me about my birth control methods. I could have told her about how many birth control babies just happen along, but didn't feel like getting into a debate.