I think this would be good for simulation games.
That is, games meant to simulate aircraft or racecars.
It would also be good for games that are war games, but are more focused on showing that war is terrifying rather than fun. If a game is made with the intent of showing people how horrifying such an experience would be, this would be good. (We need more games like this.)
But... I doubt it would actually add anything to games. It'll probably feel like more of a gimmick than anything.
Also: I'd say smell comes after vision, hearing, taste, and feeling on the scale of information obtained from it.
Vision and hearing are essential for survival, taste indicates the safety of things we're eating or drinking, and feeling allows us to manipulate our environment. Smell seems like more of a byproduct of taste than anything. While useful, not nearly as useful as the rest.
