Via the "Offsetting Behavior" blog from Eric Crampton:
Recall that books published through 1922 are in the public domain in the US; those published since then are covered by copyright…..
So any arguments about underexploitation of unprotected works seem untenable.
If this were a moving wall, maybe it wouldn't be so bad: eventually, books would come out of copyright and be released in new editions. But Disney does keep going back and insisting that nothing can ever be returned to the Commons from which they so liberally drew, and Congress loves Disney; we might reasonably expect another copyright term extension act to keep the wall fairly rigid.
I do not, by the way, blog this as a confirmed anti-IP libertarian, but as data about how copyright contributes to the actual access to and use of old books, I found it interesting.
Jesse Walker wrote on how IP enforcement can hobble cultural production in his March 2000 Reason classic "Copy Catfight."