This is good except for two things: (1) women lose their fertility at "a certain age" and if they put off childbearing for too long they might lose the opportunity and (2) if you have children late your life will overlap less with them. For that matter there is the issue of chasing a toddler around when you are 50 and less energetic than when you are 30.

It's probably not so good to have children when you are very young and not so good to have them when you are old, there is some optimum in between but unfortunately many people who put this off find the choice is made for them.