From the Creative Commons Blog:
Creative Commons (CC) has enabled a new approach to copyright licensing over the last ten years. CC licenses facilitate novel social, educational, technological, and business practices, and support productive relationships around networked knowledge and culture.
Some proposed revisions would broaden the scope of uses of copyrighted works permitted without the rightsholder’s permission. In response, it has been suggested that the very success of CC licenses means that copyright reform is unnecessary—that the licenses solve any problems for users that might otherwise exist. This is certainly not the case. CC licenses are a patch, not a fix, for the problems of the copyright system. They apply only to works whose creators make a conscious decision to affirmatively license the right for the public to exercise exclusive rights that the law automatically grants to them. The success of open licensing demonstrates the benefits that sharing and remixing can bring to individuals and society as a whole. However, CC operates within the frame of copyright law, and as a practical matter, only a small fraction of copyrighted works will ever be covered by our licenses.