The camera existing was definitely part of it, not just an indicator light.

Also Google Glass was designed to be “casual” in that you’d always be wearing them passively, even when not actively using them. Therefore you’d have to be aware of the camera on you anytime you’re in the room with someone that had them.

Apple’s aren’t the sort of thing people are just going to be wearing around all the time in casual moments. I mean, some will, but the vast majority of use cases will be purposeful, not just wearing them to wear them.