It would be nice to be able to quickly message someone outside of the game client ... ie.. "Yo, up for an alt shot?". Instead you have to start up game client, create a game, set all the params and then invite. Then..while you're chatting in there trying to find/invite others to play, the create a game window times out and kicks everyone.
Kind of a non intuitive way to create and start a multiplayer game IMO.
Chatting externally requires you to manage yet another friends list external to the game, which is a non starter for me. 1 friends list of those I'll play with is enough for me.