I worked for a guy who designed playgrounds for kindergartens, schools and similar.
He stressed the importance of spontaneous, unstructured play. As you note it leads to important social development, it improves creativity and could lead to much better academic performance into the teens according to the studies he showed me.
When he designed a playground it wasn't "here they can do A and there they can do B", but he strived to provide spaces that facilitated spontaneous play. He wanted the kids to do their own thing, and provided as many options as possible. An important factor here is that kids enjoy different kinds of play. Not everyone wants to kick a ball, some want more social play so might need a space that allows for that, perhaps a secluded sitting group.
However as you note safety is a big issue. He had a guiding principle of two kinds of safety. There's subjective saftey, if you're high up you know falling might hurt. This is what kids should learn, and it's important they get to do that without permanent injury.
The second kind is objective safety, which relates to the environment and equipment, which facilitates this learning of subjective safety. There shouldn't be rocks near by equipment which could cause permanent injury if a kid fell of the equipment. There shouldn't be gaps in the swing attachment where a kid could lose a finger, and so on.
He stressed the importance of spontaneous, unstructured play. As you note it leads to important social development, it improves creativity and could lead to much better academic performance into the teens according to the studies he showed me.
When he designed a playground it wasn't "here they can do A and there they can do B", but he strived to provide spaces that facilitated spontaneous play. He wanted the kids to do their own thing, and provided as many options as possible. An important factor here is that kids enjoy different kinds of play. Not everyone wants to kick a ball, some want more social play so might need a space that allows for that, perhaps a secluded sitting group.
However as you note safety is a big issue. He had a guiding principle of two kinds of safety. There's subjective saftey, if you're high up you know falling might hurt. This is what kids should learn, and it's important they get to do that without permanent injury.
The second kind is objective safety, which relates to the environment and equipment, which facilitates this learning of subjective safety. There shouldn't be rocks near by equipment which could cause permanent injury if a kid fell of the equipment. There shouldn't be gaps in the swing attachment where a kid could lose a finger, and so on.