You can simply use the popout chat: http://www.twitch.tv/sunspots/chat
I don’t really know what Twitch are going for with the new group chats, but since they are already working on some kind of room switching functionality, I don’t really see why they couldn’t let people ‘pin’ a couple other chat rooms, just like the way group chat rooms are saved and switched between.
Edit: Also, this is the developer forums, which is not the place for general feature suggestions/discussion.