To reiterate my points:
1. Carrying around a controller to be used with your iOS device, something designed to be sleek and simple, makes your iOS less portable, and cumbersome if you want to recreate such a gameplay experience on the go. Try doing that on a bus or a train, I can't imagine many situations where such a thing is convenient.
(By the way, if people want to do that, indeed thats for them to decide if given the opportunity, just like its for me to decide if I'd like to share my thoughts on it).
2. If you're seeking gameplay experiences that legitimately greatly benefit from having a controller, then IMO, you're probably reaching outside the scope of how of lot of games for these devices are designed. Thats why I brought up the Vita and 3DS. Those devices are more dedicated to deep gaming experiences, will likely feature libraries for deeper game experiences, and are DESIGNED to be used with controller-like interfaces from the ground up. There is no external input device necessary to carry around with you.
When you start talking about controllers for an iPhone, you may as well be talking about games experience with control interfaces that are not so simple such that they can be pleasantly controlled with a touch screen. And frankly, I think you're reaching for something that an iPhone is not meant to offer. To give you a quick example, you will not find a game that plays like BlazBlue on an iPhone, but you will on a Playstation Vita and a Nintendo 3DS. Those systems are designed for game experiences like that, and are marketed towards those who play them.
Finally, carrying around a bluetooth controller is not the same thing for me as carrying around a PSP. The bluetooth controller would be pretty much a pure accessory that has no absolutely purpose other than to sync with my iPod when/if I want to play a game on it. If, say I decide to play game on it, now I gotta prop it up somehow (and if I'm using an actual propping device, thats another thing I gotta carry around, and then I have at least two separate devices out, and who knows where and public I'll be (could be on public transportation) just to play a game.
My PSP, DS, and 3DS all have cases with close, yet padded fitting oval designs that feature internal compartments to accommodate at least three cartridges/UMDs. They all fit comfortably in my pocket. If want to play a game on them, I can, no propping necessary, no external input device to connect. Also, physical media for traditional portable gaming devices is become increasingly optional. I still prefer physical media out of personal preference, but I know of many people who buy most of their PSP games digitally and have them all stored on a memory stick. This is getting beside my point, though.
Overall what I'm saying is, if you're truly desiring controllers, I think you're probably asking for an iOS device to be a kind of gaming device it was not meant to be. An as an avid gamer, I think the types of portable game experiences that truly call for controllers are best found on devices that are more truly designed for them (at least at this point in time) That is why I brought up the Playstation Vita and the Nintendo 3DS.
