Let's imagine a world where you sign up for discounts on certain goods in exchange for allowing your Glass to randomly take pictures throughout the day. This data is mined and tagged and sorted, until one day the .gov or .mil or some hacker decides to pull it and use it for nefarious purposes.
The fact is that the nerd fantasy of getting a HUD (to track what, exactly? Ammo? Health? Some numbers in a database you've been trained to equate with self-worth?) is not worth the societal cost of losing privacy.
"But we've already got smartphones with cameras!" doesn't work--the camera is there, and likely just a change of app policy away from being always on.
This is such a shortsighted idea.