Kids distract from the modern, busy, downsized life. They're a major time and financial burden, and they only add headache. You can't make them do meaningful work for you. They get in the way in ways that were impossible a century ago. You can't hop on a plane, take off after work, or shut them away and have them mind their own business. Not like on a farm, where kids could roam free, learn independently, and help with the mountain of chores.
This is tongue in cheek, of course, but there's definitely some truth to the calculus of whether or not to have children. And it's on everybody's minds.