Playful spaces - take a swing!

Bruno Taylor is master in industrial design, and he had a question: What has happened to playing in the streets? Fewer and fewer children are playing outside in the public areas. Taylor has shaped his question as a swing in a bus stop and recorded the reaction towards the installation:

This is not a game (which is what I am studying) but it is still relevant as it deals with the restrictions and possibilities there when inviting for play in public space.

A few people actually take a swing, some pose on the swing to take a photo - which in my perception is also a form of play. Some just look puzzled and distrustful towards the alien swing in the bus stop.

A bus stop is a context for waiting, often together with a bunch of strangers. People waiting there are together even though they are not. For me at least it is a dull time, where a bit of excitement would be much welcomed. But is it acceptable for adults to play in the streets? Does the design of modern cities invite for play?