How many other people own that controller or others like it? I haven't seen one third-party controller maker release sales figures, and without them, it becomes hard for a for-profit company to justify developing a game targeted at a particular third-party controller. It's also bulky to carry in a pocket.
I'm glad you asked. When the latest AppleTV got released, one of the first items to purchase with it was a game controller. At the time there was just the Nimbus, which is the one I got. Shortly thereafter, the Steel Series Status came out. Now there are a total of six different controllers in all available. The pricing ranges from what you normally expect, so nothing shocking here.
FYI - will continue on next post as lameness filter is fucked