I find extending childhood extremely problematic.

To delve a bit further on this, I am talking about a phenomenon that has been observed in human and non-human species. It is called Neoteny. This is a biological concept that refers to the retention of juvenile characteristics by mature individuals such as floppy ears in dogs and curly tails in pigs. At the behavioral level, it appears that when the environment becomes too complex, animals delay adulthood by extending the "play" period of infancy. This allows the species to adapt to the complexities of the new environment. Physiological neoteny is also seen human (large head, flatter face, small arms, and slow development), and I think that we can make a good case that retention of juvenile characteristics extends to the psychological-behavioral domain. We now live in a technologically complex environment, and it is therefore necessary to retain juvenile characteristics to be able to adapt to it. So, extending childhood appears to be currently the evolutionarily adaptable thing to do. This is what I mean by extending childhood.