Play has changed. Take a look at the first severalminutes of Cain's Arcade on YouTube. Here is my take: I don't want to minimize the creativity Cain put into his Arcade - it was quite impressive. But, really, not long ago every kid played like this. No one came to your door from NBC Nightly News and wanted to put you on TV. That is just how kids played.
Check out an interesting article on "11 Benefits of Play" and also check out Playworks. Their whole focus is teaching kids how to play at recess. Not a type-o. When kids play, learning improves and behavioral issues decline.
And play is not just for kids. Much more to come...