I would wonder if what is really at discussion is children having ample opportunity to "be at one with nature"? And also to be creative (either alone or with others) without any interference from parents, structured time, commercially created outdoor toys, etc.
We live on some bit of acreage and our DS has access to bugs, cats, chickens, cows, dirt, plants, and toys...some commercially made and some made by him from whatever he finds. He does this alone or with us. Often on weekends, we are together exploring, picking berries, helping with yard work, feeding animals, etc.
He's had a lot of opportunity to explore alone. This has only been true since he's become older, however. We live on a river and DS has been strictly supervised outside most of the time until recently. It would be nice if we lived near other children who could just "come out to play", but we don't. Our son has learned to be self-entertaining.
Anyway, children in urban areas have other opportunities to observe nature. Like Curious George, that may mean leaving the city for the country on excursions, or else just enjoying the parks. Possibly "fly-by" miscellaneous creatures (like the pigeon named Compass).
So much needs an adult's supervision these days.
I really do think that has an affect on their spontaneity. Perhaps that also affects I.Q?
If someone is always chattering away to you about their interpretation (or knowledge) of things, how are you to work things out in your own mind? (And possibly discover something no one else has thought of?)
As a child, being alone (notice I didn't say lonely!) with the earth around and no pressing need to go someplace is very important, imo.
Listening for that "small, still voice" has nearly been lost.
