This addon does as you suggest but with a simple click as opposed to having to go into about:config. Better if you think you might use webrtc from time to time.
I can actually see WebRTC becoming very useful... I actually miss the days where the likes of IRC, AOL and Yahoo group chats were more common... I wouldn't even know where to begin if I just wanted to chat with random people who are relatively local to me today.
Not just voice/video but text. That said, I'm not sure how useful the P2P aspects of text are, but being able to send files directly would be a nice ability.