2013. They didn't take off due to privacy and legal concerns of potentially recording everything and everyone without their consent. The developers only other option would be to lock down the video stream so only their (if uncompromised) code could process the images - in highly regulated ways - which limited the function to app built exclusively by the manufacturer.
I'd like to think that what you said is true, but I think it's more likely that the reason Google Glass didn't take off is simply because it looks dorky. The general populace doesn't seem to care about privacy, as much as I wish otherwise.
