It makes absolutely no sense for AOL to charge for its Instant Messenger services.
There are literally tens and tens of messaging services which are basically identical. In each of them, you can exchange text messages, HTML messages, emoticons, transfer files, and indicate your status. Some examples are AIM, ICQ, MSN, Yahoo, Jabber, Everybuddy, Odigo, and many, many more. None of these are superior to any other, except for some advanced features (voice messaging, videoconferencing, encrypted chat) that nobody EVER uses.
So one Instant Messenger service starts charging, we move on to the next one. What's the big deal. They are all the same.