Odd Building Tops

What's with the odd roof-top structures on new Shanghai buildings. A good number of the new buildins have very strange tops, with UFOs, pyramids, and many other shapes common. And it's not just signature buildings, but run-of-the-mill office buildings. The best is the UFO atop the Radisson. I guess the idea is to stand out, but a decade or two later and these things look mighty funny.