I think that is a good point no matter the motives for making it. At some point protecting intellectual property "just because" becomes a problem, and not protecting it at all is obviously a problem, too; so where is the sweet spot? Immortal companies like Disney would probably say "50.000 years", but what would be best for humans?
What is fair to creators and their families? On the one hand I'm thinking, if you create something so great that people hundreds of years later still cherish it, why shouldn't your grand grand grand kids have a slice of that pie? On the other I think it's rubbish that one can't legally sample a few chords from songs that are 50 years old, just because some corporation happens to be fussy about it. Maybe the full work should be protected longer, but restrictions on derivative works could gradually soften much sooner?
And should it be the same for all types of copyrighted content? Think documentary footage etc. - while I would argue "fantastic" art isn't something society necessarily is entitled to enjoy as soon, when it comes to other things, the sooner it's up on archive.org the better!