If someone really came up with better input devices, the pro computer gamers would be using them. As for user interfaces, Starcraft players seem to manage very many actions per second. So the challenge is to create a user interface that's friendly and usable to "noobs" but also able to augment pros/experts to their limits. Most recent UIs seem to emphasize friendly and usable to "new users", but they neglect the case where some of those new users don't mind taking the trouble to learn to do things very very much faster.
current games are designed around KB mouse input, the kinect stuff is programmed to take advantage of the hardware. give it time.
Sentient plasmoids are a gas.