Can someone explain to me the appeal of Glass? Technologically, it's a predictive evolution: cameras, visual overlays, GPS units are smaller and more efficient.

Can someone explain to me the appeal of Glass? Technologically, it's a predictive evolution: cameras, visual overlays, GPS units are smaller and more efficient. They've been fit into mobile devices for sometime, why don't we wear them instead? I'm sure this has broader application than endless POV pictures, which is probably why they're kicking off the "If I Had Glass" campaign.