Physical controls are vastly more useful - when the control you want available can be planned ahead of time. You get touch feedback when you're operating it, of

Physical controls are vastly more useful - when the control you want available can be planned ahead of time. You get touch feedback when you're operating it, of where it is and what state it's in. You don't have to look. Missing it with your finger is obvious. Glass controls are optimal for precisely only one scenario, and that is when you don't know ahead of time what will need to be on the screen. That's why smartphones use them.