Mike Linksvayer says:

Copyright is unjust. Works created under that regime are tainted. Extreme position: the disappearing of works subject to copyright is a good, for those works are toxic for having been created under the unjust regime.

While I understand where he is coming from, I have to disagree with this position. Many works released under a highly-restrictive “All Rights Reserved” license are done so more out of laziness than anything else. If a creator creates something they wish to share with the world, but is not aware of how the system is at work to prevent sharing (many creators I find to be unaware or misinformed, generally, about copyright) we should definitely celebrate the liberation of that work. That the liberation may eventually come through the expiry of the copyright and not through a conscious act of the creator does not, in my view, taint that liberation.

While a poorly-documented copyright holder or future retroactive extension may steal this work back from us, the same holds true even for work born free. We take at face value most declarations of a free birth, but poor documentations or changes in the law may yet steal more of even these works from us (though, of course, we work to avoid that fate).

Separately, I believe that Linksvayer sees works that have spawned significant proprietary legacies (take for example, James Bond) are tainted by these legacies. In this case I agree that the acceptance to the commons of the origins of such a legacy (such as the James Bond novels) must be taken with caution, since anything building on this source often serves to promote the still-encumbered legacy more than it does to add to the commons, and may even run afoul of legal actions by the owners of such legacy (similar to the problem of clean room reverse-engineering).

However, without an effective system of cultural copyleft (which we lack, though CC-BY-SA is a fine attempt) there is nothing to prevent a fully-encumbered legacy from springing from born-free work. There we would find ourselves stuck with the same conundrum. If a proprietary television program based on, say, Pepper & Carrot became very popular, would it thus become useless as a free body of work? Would we have to move on for fear of providing more benefit to the encumbered program than to the existing free work? I hope not, but I don’t know the answer.

So, I say, celebrate Public Domain Day! Much new work enters the commons, not just the select samples that have spawned an encumbered legacy. Use, study, share, remix!