The DS touch screen is far from a gimmick, it has been utilized in fantastic ways. I think certain individuals are confusing companies throwing in all the features just for the sake of throwing in features, not looking at it from a game by game perspective where certain things, like the touch screen are great, while in others it is not. The DS has one of the most diverse and deep gaming lineups of any console, some use the touch screen RIGHT, some don't, and some just don't bother with it because it isn't necessary for the game they are creating. It is the choice of features, that, IMO has made the DS such a fantastic handheld. Probably the only thing that is gimmicky is the mic.
I know it is tough to remember that the gaming world doesn't revolve around your likes/dislikes, but if you can get past that you'll see many gaming experiences on DS that prove touch screen nor the Dual Screen are gimmicks.