Google Glass is the Crystal Pepsi of the internet. It's only interesting in that it represents a definite violation of ordinary, common, everyday privacy, but stands out as one boundary that certain interested parties are determined to invade.
EDIT: My exact thought on this subject has been that the camera needs a mechanical shutter. But I'd say thinking of Glass like sunglasses is probably also the way to go - a way to "take it off" without having to take them off (i.e. like when you put your sunglasses on your heard to talk to someone indoors).
Remember how popular the iMac (~1999) was when they started adding colors and patterns to the outside?
Google Glass is more akin to someone wearing a GoPro to a party the whole night. Not someone who pulls their phone out of the pocket for a minute or two.