To this point, the gamepad has been more meaningful for gaming than the Kinect, though neither are necessary. Whether each one lived up to its respective $100 fee would be a judgement call. Really, the best features of each are enhancements for other media and content rather than directly for games.
The legacy for each is that they stunted sales for their respective consoles before they could get off the ground. Part of that is the additional cost but it also has to be said that neither console manufacturer has been able to give a compelling reason for people on a large scale to want their gimmick/innovation. Kinect has mostly featured voice commands--nice but it's hardly going to make people reach for their wallet. The gamepad has shown off-tv play--nice but most people will prefer playing on a big screen--as well as a mix of in-game uses that varies from nifty to meaningless.
The gamepad has been a failure as a system-selling feature. Kinect 1.0 was a huge success initially, which makes the fall of Kinect 2.0 all the more gruesome to watch.
Both should serve to remind console manufacturers that hardware gimmicks/innovations normally need compelling content in order to thrive. Yes, there have been aberrations but banking on that is a gamble. The assumption that developers will use your gimmick/innovation simply because you build it is deeply flawed and a good way to get your console ignored.
