Defending copyrights held by small fry is usually of negative value, which is why they do their best to give all the material away themselves. They want the exposure more.

The counterfactual to making an illicit copy of Thriller might conceivably be that you pay for an official copy. The counterfactual to making an illicit copy of Everybody Needs A Robot is not that you pay for an official copy. It's that you go do something else, which is worse for the artist.