8-Ball is too strategic. There are too many options, and it's too hard to explain to the viewer what's going on. They just get confused. Also, it can be very slow at times.
Bank pool is a definite no-go. Unless you have the top players, it's just a mess. The idea is to simplify and speed up the game, not slow it down by trying shots that miss half the time.
As far as I'm concerned, 7-ball is the game for TV. It's fast, obvious, and can be very exciting. I admit, it does lack depth, but it is good for TV. As far as I know it was actually designed specifically for this purpose.