I have a few ideas,
A big one would be a player defined functions, like you can shorten commands or change them to suit yourself, that why you define the lingo and the language of the commands, plus a return to default one each one just incase.
or maybe add a right click or something action to view possible actions? might come in handy when you want to stop attacking someone and not have to write it? or maybe just a better tree system.
Also maybe an option to stop a tree from repeating so often, say you are upgrading your stats, you can set the thing to clear just the last data entry and update it with the new stat count. etc;
Thats all I can think of for now.