The controller solution is simple and it's 100% down to Apple to allow it.
There is no reason on earth why they cannot make an external iController as a user option for games. As they do the plug in adaptors for camera cards.
In any game, the developer can put a user option whether to use on screen controls or use the external iController.
They would sell millions of them, and allow people to play many games properly on their iPad.
Yes, some games are very suited to on screen controls. Other games are totally ruined and virtually unplayable without a real controller.
It's up to Apple to give people the option.