I'm all for it!
Population size shouldn't be a problem since most people would turn it off.
I always hated the lack of general chat in this game, because being part of a group is the main way to socialize and it gets very cliquish/plus if you don't wanna join an FC it's very lonely for an MMO.
And it would solve a lot of NN problems, since a lot of people want to be mentors just to have such a chat.