I'm sick of the word "gimmick" being tossed around every which way and used only when it's to express discontent with it just because "I don't like it, therefore it sucks and it should never progress!"
3D and motion controls both have their interesting mechanics behind them on how they can be used, so say "3D can fuck itself! I want to stay in 2D!" and vice versa with Motion controls is pretty much a testament to how people just hate change of any kind.
Personally, I think 3D has a lot of potential, moreso in video games than in movies because it can be brought to an interactive level, bringing you to a whole new level of immersion and an extra dimension to toy with. Motion controls are a bit hit and miss with me, but so long as it's not shoved down my throat or utilized in a less-then-ideal way then it's an interesting mechanic that can really smooth controls.
I do think that 3D has more potential than motion controls do at this moment since the Wii has already popularized motion gaming, the only problem is that it's not quite perfected yet or used in a whoely new way.
I, for one, can't wait to see what the future holds for these mechanics. If they fail, they fail, and the industry probably will stagnate in some areas. But if they succeed then it paves the road for even more innovations and new mechanics, so long as they are utilized properly.
Also, as I've asked before, have any of you actually played a 3D game before? You cannot compare 3D movie "gimmickery" with 3D game "gimmickery", the two don't even use the same technology. I've played WipeoutHD in 3D, and let me tell you it was practically a whole new game. I wear glasses and I didn't find it that uncomfortable or hard to use.