Apparently there is a provision in the DMCA that every 3 years the librarian of congress has to decide if it is still valid or if changes should be made. The copyright office is in the library of congress hence why the librarian makes the decision.
Apparently it took them a year to make the changes they did so the next time they have to start reanalyzing is two years from now.
Why this change is because the librarian of congress felt it was a valid decision
Section 1201(a)(1) of the copyright law requires that every three years I am to determine whether there are any classes of works that will be subject to exemptions from the statute’s prohibition against circumvention of technology that effectively controls access to a copyrighted work. I make that determination at the conclusion of a rulemaking proceeding conducted by the Register of Copyrights, who makes a recommendation to me. Based on that proceeding and the Register’s recommendation, I am to determine whether the prohibition on circumvention of technological measures that control access to copyrighted works is causing or is likely to cause adverse effects on the ability of users of any particular classes of copyrighted works to make noninfringing uses of those works. The classes of works that I designated in the previous proceeding expire at the end of the current proceeding unless proponents of a class prove their case once again.
So evidently the Register of Copyrights suggested that this change be made and the Librarian agreed.
http://www.copyright.gov/1201/2010/Librarian-of-Congress-1201-Statement.html