When the U.S. Constitution first addressed the issue of copyright, the world was just entering the mass-produced Industrial Age. The clause (Article I, Section 8, Clause 8 for those keeping score at home) sez:
"To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries."
Originally copyright was limited to 26 years, with an option for an extension of another 26 years if the creator so desired.
The 18th century legislators who drafted the Constitution clearly felt few if any creators would live long enough to see their original work go out of copyright at the end of 52 years.
Well, times and circumstances change. For one thing people began living a lot longer. For another, corporate “personhood” allowed non-human entities to lay claim to work they had no direct input to creating.
Now, the concept of corporations -- the original concept -- was not bad: A business entity that came together for a particular purpose for a limited period of time.
And once that purpose was achieved, the corporation was disbanded, its assets distributed among the shareholders.
But as the eminent philosopher C. Lauper once observed: “Money changes everything.” Corporations bribed politicians to change the law so they could stay in business forever, and could in fact expand into businesses far beyond their initial prevue.
Marx wrote of workers’ alienation in modern industry, but that’s nothing compared to the alienation suffered by modern shareholders. Shareholders, who often have invested blindly in mutual funds that chase down the best return for their dollar, have no first hand knowledge of the human beings working so hard to pay them their dividends.
Since they have no direct link to any of the businesses the mutual fund invests in, they don’t care how their money is made so long as their money gets made.
Corporations, hearing only the relentless drumbeat of “more-more-MORE” from the mutual fund managers, use business practices that would make Morgan the pirate blush.
This means, for creative types, that once a corporation sinks its fangs into an intellectual property, it’s never gonna turn it loose.
Copyright meant different things at different times in different cultures.
Japan was notoriously lax bordering on the whimsical when it came to copyright enforcement. For a long time, any recording released in Japan had only a 20 year copyright, then it became public domain.
As a result, big non-Japanese acts were loathe to officially release records in Japan. In a compromise move, they’d go to Japan and record a live album at a stage show, which would then be sold in Japan.
When these live recordings went P.D. in Japan, the original recordings, still officially unreleased in there, remained safely under U.S. and / or European copyright.
Of course the Japanese -- and the Chinese, and the Indians, and the Koreans, and the Vietnamese, and the Thais, and the Filipinos, and the Malaysians (not to mention the entire Middle East) -- pirated the ever-luvin’ s4!t outta everything, but those original copyrights remained sacrosanct.
Conversely the Europeans, in particular the French, took a much more respectful view of copyright re creators’ rights. Creators might sell rights to their work, but that didn’t give the new owner carte blanche to do as they saw fit with it, nor could they profit off it without kicking something back to creators and / or heirs.
They also stuck an extremely lengthy term of protection on copyright: The life of the creator/s plus 70 years before it becomes public domain.
At first this seems like a fair idea, but it actually works against both the original creator and the culture at large.
At a certain point, ideas, characters, concepts, stories, and techniques need to be “released into the wild” to be used by the culture at large in such a way as to build off of them, to expand humanity’s cultural capital.
We do not forbid people the right to use vanishing points in their paintings simply because Filippo Brunelleschi pioneered the technique 700 years ago.
Likewise, a still living creator is not harmed if a work remains popular even after falling into P.D.
If anything, it's continuing popularity only further promotes the creator's work and career.
Irving Berlin lived long enough to see "Alexander's Ragtime Band" fall into public domain. Some how I don't think he missed any meals because of this.
But with soulless amoral corporations using their ungodly influence to guarantee more and more money for themselves, we now see ourselves in a media environment where there is no protection for the smaller creator.
At the same time we can acknowledge that the corporations have spent a lot of time and capital promoting their characters, concepts, et al., to the public; it is neither unfair nor unreasonable for them to expect some return on their investment.
But when a corporation is the bogus “creator of record” for a work or character, when does said work enter the public domain? When the corporation is sold off (if ever)? But then the property is usually sold to another corporation, and the cycle begins anew.
Copyright, as it exists today, is much too long. It needs to be limited to a more reasonable period, say 50 years at which point it enters the public domain.
Corporations (viz. Burroughs and Disney and Lucas) frequently hold trademarks on specific character designs; unlike copyrights, trademarks are forever (or at least until abandoned).
It would not be unfair to allow trademark holders the privilege of being able to advertise their product as the “official” version, while still allowing earlier versions to fall into the public domain & fair usage provided such works were noted as “unofficial”.
Such unofficial versions would not dent a major corporation’s revenue stream. For one thing, if a corporation thought they’d make a buck off something, they’d do it: Convention sketches, fan films, slash fiction, etc., clearly aren’t worth their effort.
 This explains the huge number of “Live At Budokan” albums.
 For a specific recording of a specific performance, copyright only extends 50 years, even though the underlying source material may stay in copyright much, much longer. One could not remake a European film from 1960, for instance, without paying the original writer and director though one could show the original film without reimbursing them.
 The irony, of course, is that rarely does a P.D. work bring the new packager any significant reward unless and until a new creative spin has been put on the material; viz. West Side Story / Romeo & Juliet.
 Burroughs has trademarked the image of a nearly-naked-clean-shaven-white-guy-in-a-loin-cloth as Tarzan, even though the original books are falling into public domain. Try making a Tarzan movie based on a P.D. book, however, and you will find ERB Inc. lawyers swarming over your creative assets. One wonders if a drastic redesign / re-imagining of Tarzan would escape such legal scrutiny, say a naked bearded version of the character, or one where he wears some modified form of jungle fatigues. Likewise, many of the earliest Mickey Mouse comic strips are now public domain; what if one filmed them in live action with human actors? Points to ponder…
 Paramount Pictures and Lucasfilm and Stephen King have long since learned the wisdom of letting fans make films based on their properties so long as they don’t make money off it. Good or bad, the final product only promotes the Star Trek / Star Wars / Stephen King brand, so essentially it’s free advertising.