Anarchy Online way back when had a "local chat" (I forget what it was called) where who saw what you typed depended on the physical distance between players. It worked *wonders* for immersion. People still used out-of-game voice systems for technical communications, obviously, but for reasons stated above, but for immersion and roleplay purposes that chat thingy was great. In cities you could hear people talking in the square and then lose some strands of the conversation when you moved out. Or you could actually go into a corner and whisper things and someone might overhear (or eavesdrop). It was not really cumbersome because you always had other chat lines and oog voice to use if you wanted to get things across.