It is essential for one's erudition, which historically has been considered important for an informed citizenry that knows the good and the beautiful.

Take the mid-20th century canon of films, works by directors like Ozu, Kurosawa, Godard, Truffaut, Antonioni, etc. These are recognized as classics of film art and part of our general cultural heritage now. However, due to changes in legislation in the years since they were made, they are still under copyright, and so a person would have to spend thousands of dollars to legally obtain a cultural education that, in this day and age, ought to be available to anyone regardless of their means. A person pirating such films is not necessarily doing it for daft entertainment (because often these classics are not particularly fun and entertaining), but simply to learn and be familiar with the canon.

And before you say that one can turn to the library instead of torrenting: many countries around the world never had well-stocked libraries to begin with. In fact, in some of these same countries it can be less than straightforward to purchase the content even if one has the money to spend.