1/ The first concern pops into my head is having a recording device nearly always on. In reality, there is no way you can prevent people to take photos and/or videos using smartphone when something interesting is happening in the public. It takes less than 5 seconds for people to take the phone out of their pockets and start recording. Then what's the real difference between camera on the face or camera in the pocket?
2/ The Glass-Hole issue. People always blame the camera as the ultimate evil. I'm not that sure. Remember, the original Google Glass was basically a piece of not-that-useful-to-put-it-nicely gadget that costs $1500. Honestly, back then, I thought whoever is buying those stuff that just overpaid nerdy douchebags (I'm thinking that way mainly because I cannot afford it). I'm not sure having a camera is the biggest issue; but having a camera is probably the biggest issue that you can publicly talk about.
3/ Trust issue, i.e. whether Google/Apple/FB are secretively collecting those video feed. Or even worse: what if the business model of future AR products depending on collecting those video feed.