For AR glasses the current best option for tracking is inside out tracking so the camera would basically always be deployed. I don't think we have to go so far

For AR glasses the current best option for tracking is inside out tracking so the camera would basically always be deployed. I don't think we have to go so far as assigning nefarious intent here, there are a lot of reasons they're designed as they are. For example your proposed solution is bulky, expensive and prone to damage, so there's plenty of non-nefarious reasons they don't have it operate that way.