I don't know why kids don't use them, unless it's some kind of feng shui issue...bad chi and all that. What is it that makes a public area, no matter how big or small, attractive? Here's a wonderful article on the art of playgrounds that gives a few clues.
There's something about these empty benches and lonely swings that evokes a bittersweet nostalgia every time I walk past one. They make me sad, but at the same time, as long as they are set aside as playgrounds, no matter how poorly maintained by the city and the neighborhood, there exists some strange sense of hope.