A commenter over at Slashdot gives an insightful explanation of why we have the DMCA even though it is, umm, not worth having:

All of this is just my rather long-winded way of trying to explain why so many people (people in government in particular) are hooked on strong IP law (including the DMCA, DRM, and anti-circumvention), and proprietary software: they see it as a way to ensure that the U.S. can still make money doing the only thing that we seem to be good at. It may not seem at first glance to make a whole lot of sense, particularly to non-Americans, but I’ve met a lot of fairly powerful people who are very, very nervous about where the New/Global Economy is headed, and how the U.S. is going to maintain its standard of living [2] in the future.

Why strong IP law is so attractive [via Slashdot]