This right here is 100% a feature I whole-heartedly approve of considering that they now have multiple instances for some zones. It would solve so much friction between role-players and non-roleplayers as people who are not into it can just never enter those instances, and role-players have a place where they can roleplaying without too much immersion breaking shenanigans, which would if it happened be fully reportable as it would be obvious the person is a griefer and get banned SOLELY from RP instances.
There are so many issues something like this would solve.