I think you're referring to "yuppies," and that's nothing new.. and I'm often irritated by people's apparent materialism or shallowness. But the idea that not having children necessarily equates to selfishness or immaturity is not always true (or even very often true, imo.) Come to the deep south where some families don't know when to stop having kids, even when they cannot support them (or don't even seem interested in raising them).
It cuts both ways.
I agree---
Have children because you want them.
Have the number of children you can care for.
But don't have kids so you have enough 'field hands' or 'someone to take care of you when you get old'. That's wrong.