This whole idea is one of the reasons I love Pinkie Pie so much. It's like as you get older, you think you have to act like an "adult" and only think about "adult" things rather than taking everything life gives you.
"When I was ten, I read fairy tales in secret and would have been ashamed if I had been found doing so. Now that I am fifty I read them openly. When I became a man I put away childish things, including the fear of childishness and the desire to be very grown up.”
- C.S. Lewis