Being non-traditional in just about every sense, I got snipped at a childless 23. If you asked me why at the time, I would have said that the world is small and is getting smaller with every child. I would have also said that I didn't need a surrogate ego to justify actions, which, if directed to myself, could only be described as selfish. I guess I saw so many of my lefty friends with kids (first one, but almost always another or two) signing up for private schools, thinking school vouchers weren't that bad an idea, suddenly thinking cities weren't good places to live, buying gas guzzling minivans in anticipation of all the wonderfully enriching lessons, sports, and privilege enhancing circles to which they would transport their kids.
Twenty years later, I don't regret not having kids. It helps that I work with a lot of students, and so get a lot of vicarious parenting in without a lot of the sticky, smelly stuff. What I do regret, is thinking ill of people who did. Many those friends raised some really interesting people. I still wish they didn't drive those gas-guzzlers though.