Having built one myself, and having watched it be played on and in unexpected ways, and having first-hand seen how it fails, I sympathize when a play-garden for children doesn't work out as intended. But this failure takes the cake. Obviously a lot of money went into it, but neither the designer, the builder, the homeowner, nor the American Society for Landscape Architects recognized the danger of a steep grass hill next to the exposed pointy corners of granite steps.
Additionally, this garden is located in San Francisco, where the scarce water supply will have to be used to irrigate all of that grass. And some poor schmuck will risk a nasty fall every time he mows the hill.
The ASLA gave this garden a big award, despite their very own code of ethics, which states that "The profession of landscape architecture, so named in 1867, was built on the foundation of several principles: dedication to the public health, safety and welfare, and recognition and protection of the land and its resources." This is a perfect example of artists losing sight of everything except aesthetics. Being a product of art school myself, all I can do is sigh. How very typical.