> Why allow them to extend it at all?

Marvel's an interesting choice, because the comic book depiction of Iron Man (for example) came out in the 60's, and almost certainly didn't make anywhere near the kind of money that the movies did. I'm not generally opposed to copyright holders getting some revenue from the later adaption of their work, especially in situations like that.

5 years is cutting it really close for your typical film adaption of a book: the first Twilight and Harry Potter movies came out 4 years after their books, and I could definitely see movie studios just waiting an extra year to cut out the original authors.

My ideal world would see original authors retaining these kinds of royalties for prolonged periods of time (maybe 40 years or the life of the author, whichever's longer), but losing their monopoly rights in a much shorter timespan: basically, for the first 5-10 years copyright works the way it does today, but beyond that anybody's allowed to make derivative works, in exchange for some legally-mandated revenue slice.

> the first Twilight and Harry Potter movies came out 4 years after their books, and I could definitely see movie studios just waiting an extra year to cut out the original authors.

So Rowling only gets to be some 8 figure millionaire instead of a 10 figure billionaire? That's so unfair.

> My ideal world would see original authors retaining these kinds of royalties for prolonged periods of time (

The prolonged period of time should be 18 months. I don't think the concept of "royalties for adapting someone else's work" is severable from the concept of copyright. These things are either the same, or royalties are some subset of copyright.

Even just re-typesetting a book is an adaptation as far as these things are concerned.

Right now, a copyright holder has a monopoly on their IP: they alone can decide who can use their works, and at what price, for the entire duration of their copyright. My suggestion was that that monopoly should only last a couple years (5? 10?), and then after that, it's a free-for-all. Re-print the book, adapt it to a movie, whatever, with the caveat that some fixed share (say, 1-5%, idk) of your revenue is owed to the creator.

The way I see it, that's the best of both worlds. If your goal is non-commercial in nature (e.g., game preservationism), then you're free to redistribute for free. If your goal is commercial, you're making money off of someone else's work, pay some token royalties, but, here's the big "but": the original author doesn't get to say "No, you may not adapt my work this way".

It even works for software copyright, with the caveat that you'd need to put some thought into how to deal with multiple claimants of royalties would work (since owing 50% of your revenue to 25 different authors seems excessive). Maybe have a cap of, say, 10% that, after reached gets subdivided based on some criteria.

18 months is flatly too short. Most creative works take longer than that between completion and market. You have to give artists some time to attempt to extract value from their work. Listen: J.K. Rowling is an evil bitch, but the world loved her work, and she was compensated as such. I feel the same way about Notch, of Minecraft fame. Guy's a dick, but it's hard to say he stole much of his fortune.

Respectfully, this isn't so much a coherent set of principles about the limited monopoly copyright grants, but rather fan service. Copyright doesn't draw distinctions between video games and player piano rolls, and why would it? What would lead any of us to believe that we'd ever alter copyright to forfeit rights when things are DRM'd? One of the complexities of copyright law is that it's harmonized across much of the world, so you're asking for radical changes not just to US law but for all of Europe as well.