Care to expand on that? Green roofs have a lot of benefits when properly planted. Insulation, reduction of the heat island effect, absorption of rain water to slow runoff into public sewers, and just sheer beauty.

The key is “properly planted”. It looks like they wanted turf grass to support foot traffic so they could use it as habitable space. Turf grass needs a ton of water and maintenance to support that kind of use so it isn’t really an ideal choice for a green roof. Drought tolerant prairie plants and plants adapted to thin, lean soils are what you want. It’s been a while since I read up on this so I can’t speak the details, but turf grass ain’t the thing.