Gosh, we wrestle and play as well, I never win though. :)
Why do I think play time is so important? Because it stops time. When we're in the moment, we jump into some kind of time warp where the world around is is almost non existent and playing can really easily put us in the moment.
Being swept up and lost in the moment, that is so big for me. I think you really nailed it there.
Thank you @walkerland. She mostly wins... also I'm ticklish and she isn't!