Interesting perspective (and one I can agree with), but I wonder if he would feel the same way today with such a large population who have fallen into a state of arrested development. It seems that there is no end to people amongst my peers (mid/late 30s) that not only never put away their childish things, but also never took up "adultish" things. For instance - those that spend more time of video games than providing for their families. People more interested in Facebook gossip than their country being at war.
Enjoying "childish" things is perfectly fine and even healthy, as long as we are adult enough to keep them at the proper priority level in our lives.