Copyright is an exchange. The government protects content, for a limited time, in exchange for the "owner" releasing it into the public domain.
This leads to the biggest problem with Copyright today: The length. When copyright was a 14 year term followed by an optional, one-time 14 year renewal, it was a sane trade-off. You get a monopoly on this book you wrote and in exchange, the public gets full access to do whatever they want with it in 14 or 28 years. If you grew up loving a story, you could write a new story using that character when you got older.
Nowadays, though, copyright length is too long. If my younger son (age 7) reads something published today that he likes, he'd need to wait around 95 years (depending on the situation and assuming no more extensions of copyright - which is a big assumption) before it landed in the public domain. Since it is unlikely that my 7 year old will live to 102, his children or grandchildren might benefit from that work going into the public domain.
This whole system was supposed to encourage authors to produce more works, but if I (at age 39) publish something today, how does it encourage me to make more works when my work is still under copyright and I'm 125 (or would have been had I still been alive)? Is an Isaac Asimov story published in 1950 really encouraging Isaac to write more because it remains copyrighted until 2045? (I can see it now. Zombie Asimov rises from the grave and, after a light brains snack, locates some typewriters and begins work on five new novels.)