You know what else can steal your passcode with a glance? My eyeballs.
You can't do that with just your eyeballs.
Google glass didn't make that possible, the invention of the video camera did. Plenty of those around -- often in compact form -- with or without Glass.
Not at the distance from which a decent camera (as discussed in the article) can capture it, you wouldn't -- what Glass can do from 3 meters away, the camera they tested in the article could -- with greater reliability -- through a window 44 meters away (four stories up and across a street).