Copyright is much newer than books.
I personally feel our copyright laws are too rigid, but that doesn't mean copyright shouldn't exist.
After x years, any book should be free to read, after y years, it should be free to be incorporated into AI models, after z years it should be in the public domain.
I don't get your point. Because we can, we shouldn't...?
The first U.S. copyright law set x = z = 14 years. That's why many people think copyright law is out of control.