One word: Speechbubbles. In most MMOs its super difficult to talk to the people near by if there is no voicechat or mic available to you. And you dont want to private Chat in every situation. Especially in an active. combat system. Speechbubbles can fix this problem pretty easy and simple. It also Supports the idea of roleplaying in your game.
I think it fits in this game very nicely and Supports the task to meet strangers for forming up guilds.