> To sum it all up, I think the 'killer app' here is the one that's so simple it seems kind of self-referential - having a display on your face instead of in the world.

The problem is that, at the end of the day, that's just a feature, not a benefit.

It reminds my of the ongoing push for speech interfaces. Supposedly they are "more natural" but in reality, even when you have a screen, the keyboard is still significantly better (even if it's virtual like on a phone)