The US constitution's copyright clause says "Article I, Section 8, Clause 8: [The Congress shall have Power . . . ] To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries." That is based on Queen Anne's Law from England, the worlds first copyright law, which was the ruling class' reaction to the Gutenberg press. That invention threatened their stranglehold over the flow of information.
The original 1790 copyright law in the US allowed for a 14 year term renewable only once. They understood that this was locking up ideas as property, which is a form of censorship. That is why its length and scope were strictly limited. Now, it is nearly perpetual and covers all kinds of frivolous entertainment that is clearly not the useful arts. Popular Music, Hollywood movies and anything on the idiot box are only frivolous entertainment.