Unfortunately there aren't a lot of AAA titles that really take advantage of motion controls in a natural way. Super Mario Galaxy is still one of the best examples of motion control implementation around. It does allow you to lay and play on the couch and you don't have to have both hands in one spot, your arms are free so you can actually get more comfortable but again it depends on the game..
Now should all games have motion controls? My answer is no, not every game is suited to that and that's why Nintendo made sure they still had buttons. I think motion control will continue to evolve and become the industry standard but they'll always be a place for traditional controls, I mean you can still buy arcade fighting sticks! They'll always be a market there.
