Controls are definitely the limiting factor at this point. I've tried a few console and PC game ports via Apple Arcade recently, and they all run great but the touch controls are really clunky - especially when they try to emulate analogue sticks.
It's about time Apple took a stab at a games controller, leaving it to 3rd parties hasn't created enough momentum. An Apple take on a gaming pad would be interesting, especially with some sort of MagSafe iPhone mount. A controller also seems a natural expansion for the Vision Pro.