The purpose of intellectual property law has very little to do with Matt Yglesias being able to enjoy a wide variety of new music. The purpose of intellectual property law is to protect the intellectual property created by artists so they are rewarded for their efforts. The purpose of intellectual property law is to punish people who steal that which isn’t theirs.
The point of intellectual property law is to benefit consumers, not producers. I don’t really want to turn this into an ideological food fight, so I’m eager to note that libertarians like Julian Sanchez and Tim Lee have the right take on this. I note that this issue is specifically addressed in the Constitution, which says that patents and copyrights should be granted “for limited times”i.e., not as a transcendent moral rightin order “to promote the progress of science and the useful arts,” again, not as a matter of transcendent moral right.