If you go back to the original intent of copyright law, it was for the creator of a work to be able to profit from that work for a while, and then the work would belong to the public...which could in turn expand, improve, or otherwise do anything they wanted with it. It was to prevent information from being throttled.

Ignoring all of the "best available print" issues, I'm firmly pro-public domain. Without it, most printed works that are now considered classics (including those by Shakespeare, Poe, Twain, and scores of others) wouldn't have been distributed as widely, and some of them may have remained relatively undiscovered (well, probably not Shakespeare, but you get the idea). As it stands now in the US, anything published before 1923 (and by published, I mean distributed to the public) is in the public domain UNLESS there is only one extant copy, and then the person who owns the copy can regain its copyright. (This is probably what happened with the guy who owns the Edison Frankenstein film.)

When I lived in Taiwan 15 years ago, copyright only protected foreign (i.e., American) films that were under 35 years old. There were LOADS of DVDs of pretty much any classic film that you could name, and they were relatively cheap (usually around $2-3 US). Most of them were ported over from VHS or laserdisc, but they were usually of passable quality, and many of them didn't get US releases until years later. I loved it.