You were the one who claimed that most would-be pirates were discouraged from doing it prior to the invention of the printing press. Guess what? The high cost of making copies (and the relative lack of literate people to share them with, assuming that the author himself was even literate) discouraged authors from writing things down too.
True.... which is why most creative works that had any chance of distribution were patronized by wealthy people.
Oh, and the library of Alexandria had money to pay its workers to make copies as well, so that's why it worked. Relatively speaking though, such patronized copying facilities were rare enough that they did not practically pose any threat to the initial creator's exclususivity.
Authors really just don't engage in self-censorship as a means of control.
Why not? Publishers do it all the time.... Region control on DVD's and DRM are perfect current examples of self-censorship... although not necessarily placed there by the creator personally, the publisher was still authorized by the creator to make copies of the work, so the creator would certainly be a willing participant to having such restrictions, even if they did not put them there themselves. Of course, the incentive behind publication in such cases has more to do with monetary reward than anything else, and I don't actually advocate such incentives as being worthwhile in the first place.
But outside of that, do you seriously think that all created works are published? Do you think that everyone who makes a creative work even *wants* to always publish it? Costs for creating works that one does not intend to publish is not necessarily high... and may often be something that is just a natural outpouring of that person's creativity, rather than a specific endeavor that is undertaken by the person to specifically create a particular work, so the matter of time investment in creating the work is immaterial. The simple fact that they have created the work at all is sufficient incentive for them to create it. This happens ALL the time... probably millions of times every single day, in fact.
And of course, such self-censorship is extraordinarily effective as a copy-control mechanism, because after all, how anyone copy the work if they don't know it even exists, or if they did, because they just don't have access to it? But the problem with this is that self-censorship does not offer any benefit to society... society cannot be enriched by a creative work that it does not have access to, so copyright gives such a creator the means to control their interests while still publishing (and thereby ideally helping to enrich society through an availability of diverse creative works).
Copyright, from an author's point of view, is a way to recoup their investment.
If that were true, there would be no point to explicitly putting things under something along the lines of a creative commons copyright license where the intent is to give away the work for free. What investment can one possibly recoup with that? Such copyright distribution mechanisms still differ significantly from public domain because they generally still have provisions in place on the purpose or how it is copied, such as allowing free copies for educational use or personal study only, or allowing free copies as long as the existing copyright notice and attributions are kept intact.
Copyright is, and has always been, about control... no more and no less than literally control over the "right to copy". The argument I am suggesting, however, is that allowing the creators to possess such control for a limited time even while they distribute the work is ultimately beneficial, since it gives those creators an incentive to publish (and ideally enrich society in so doing) where they may have otherwise utilized self-censorship as their preferred means of copy control, and society would not have benefited.
Personally, I would drop terms to a year, with numerous opportunities for renewal, but with overall maximum lengths that were still quite short (probably no more than 20 years or so, and less in the case of some types of works, such as computer software
If it were up to me, I would drop the terms of creator-controlled copyright to durations that were largely a function of the style of work itself, since the style of work typically impacts the duration of cultural relevancy for the work in the first place. Paintings and other material works of art would have the longest copyright duration, extending for the life of the creator plus 40 years. If the work was created by a company instead of an individual, then it extends 40 years past the date the creation is first published or publicized as being publicly available to see or obtain. Books would typically have the next-longest copyright duration of 25 years from the date of publication, as long as the book was not of a type where it fairly quickly becomes obsolete (such as a non-fiction, encyclopedic, or reference book where a new edition of the same book is published regularly with newer information within). In the latter case, the duration of the copyright would be the lesser of 25 years or double the length of time that the information is outdated (to a minimum of 5 years). Things like digital photos would have the same copyright duration as a book, 25 years after the date of publication. Movies and music would have a copyright duration of 10 years from publication date, and software would have a copyright duration of 5. If any extensions were to be allowed, I would argue that there should be an exponentially rising fee structure for such extensions so that practical limits are still placed on its duration (any more than about doubling the initial copyright duration should be so expensive as to exceed the annual GDP of a major country and thus be prohibitive), and even then, I would advocate that no more than a single extension could ever be applied to any work. After expiry, I would advocate that the work would fall into a kind-of-controlled public domain, where one is nearly as free to copy the work as if it had been public domain, but with the caveat that all attributions be maintained, and that the original copyright (and duration) be included with the work so that it is clear who originated the work and when, since that may have historical significance, as well as makes it clear that all of the original copyright terms have expired, and the work can be legally copied quite freely, subject to those limitations. Of course, no compensatory claims can be made by the holder of a copyright after their control of copyright has expired.