Maybe as a culture, the solution is to really push, "It's okay to not have kids! In fact, don't have kids unless you really, really want them!"

I think that would help. A lot of people seem to have kids just because it's, y'know, what people do (i.e., general societal expectations) or because of specific expectations of people they care about (e.g., spouses). Or because they internalize these expectations. And it is only natural that when you undertake a project you're not really committed to, you don't do a great job. Which is fine if it's a garden or something but not so much if it's a child.