Taxonomies of Lost NYC Playgrounds

My wife works on the playgrounds in Central Park and tells me that monkey bars with over 9 feet of fall height and kids on tire swings right below them (which I cringe at as "collateral damage") are, indeed, a thing of the past. But many beloved spaces are receiving redesigns with the original creative vision in mind -- but also years of community feedback to benefit from. These are some of the most trafficked spaces on earth. From the outside looking in, the Conservancy has always struck me as a great institution; they strive for creative excellence while still seeking to understand the unique needs and constraints that come with maintaining an island of public space in the densest city in America. Just like our industry, great engineering is the art of careful compromise. The fact that it's not one big rubberized parking lot with legal disclaimers posted is a huge testament to their creativity and humanity.

I'm missing some context here- what happened to these playgrounds? Why have they gone missing? For example, it looks like Central Park still has a lot of playgrounds. http://www.centralpark.com/guide/activities/children-s-activ...