Maybe, but I also see an issue of convenience, too. If the controller is external, it’s no problem if I’ve an otter box on my iPhone, but then I have to carry a separate controller. And if not (like this device), then it looks like I have to take off the Otter box just to game.
Whereas a 3DS/2DS is pretty much already complete with a controller, and probably more durable than any iphone. Because believe me, I drop things, and I prefer to not take valuable communications devices out of their otter boxes just to play with them.
But I guess this controller is really for people who don’t mind so much anyway.