I don't know if my daughter and son-in-law considered rubber ground cover, when they fixed up a play area for their children. It sounds like a perfect choice. It doesn't deteriorate ,it's soft, keeps down weeds, and it dries quickly - all great pluses.
The kid's play area right now has wood chips on the ground. It causes problems. The kids play with the chips, putting them in containers and dumping them all over the yard. The chips take quite a while to dry. Both kids have gotten slivers from the chips.
I hope schools are using the rubber ground covers on their playgrounds.