Sorry for "unburying" this topic, but yea, this should be a GREAT addition. I was just having this problem and searched for any topic with this.
Following the scenario here, I also think 2 other things should be added:
the ability to "auto-kick" already connected users with a username connected (I know we have discussed this already, but I thought it would be a must-have on 1.6.2 but it wasnt lol). and the room ID or room object to onJoinRoomError and onCreateRoomError.
But back to the topic, yea that is a great addition, cause right now in order to make a workaround that I have to set user vars and pull user lists just to determine who is the owner.