In my personal experience as a meeper, I find that when people use underscores in their usernames or town names, it gets a little confusing sometimes (and i would imagine this confusion is even greater for new players).
here's an example. i push tab and don't recognize RandomPlayer235, so i do /t add RandomPlayer235 to invite them to my town, but they are already in the town of "Sample Town", so I /t Sample town to check out their town and it says "sample not registered". Then i realize it was supposed to be an underscore there and have to retype my command.
is it just me or do others think we should at least display the underscore in the chat so people (especially new players) know what is supposed to be there instead of guessing when it is and isn't an underscore.