Better not...... who does not know the feeling you get when you click on a button and your computer starts insalling and changing things...... It is better to keep it like it is now. We all love the program, not only because it gives a feeling that you can actually control what happens to your computer. Going to the site to install the next updated version helps to generate this feeling. Specially for people who do not know so much about pc's and processes on it.
I am not sure if this is already mentionned nor do I know if it is already worked on and covered with "cleaning all user accounts"...but.... Could there be a way that ccleaner also deletes all the typed e-mail adresses in the drop box of the log-in screen on MSN-Messenger? I would like that very much.