That's the entire deal. It's better for everyone, better for art, and better for tech when information and culture is freed and people can incorporate it into their own works as well as learn from and build on what came before them.

Copyright only protected those works for a limited time to encourage the creation of new works by making financial success possible but not perpetual.

In a world where we can publish globally in an instant and at near zero cost, seven years or so is plenty of time to make investment worthwhile, no matter if that investment is in time, talent, or R&D. It's not as if the copyright owner (which for commercial works is almost never the same person as the creator) can't make money on something just because it's in the public domain either.