This is a great explanation. I feel the same reasoning applies to 3D movies, which I try to avoid because for me they add nothing while costing more and giving me a headache.
Regarding your last paragraph, there are indeed situations where engaging other senses makes sense. I remember visiting a museum about the different climatic regions of the world. One of the installations was a dark room with huge video walls showing desert imagery with duduk music playing, while the room was heated to probably >30°C. In combination, this was really intense.
I would visit the "Smeller 2.0" (funny name, by the way), but I agree that it probably wouldn't be too useful as an enhancement of regular cinema.