Say I want to write a screenplay and produce the resulting film, for profit, but I am literally unable to have any ideas whatsoever unless I base them on book that I read. With this in mind, and with this sole motivation, I buy and read the whole collection of Brandon Sanderson's novels and create a screenplay based exclusively on their content, for I have no ideas nor experiences of my own. I already paid when I bought the books. Why would I need to pay Brandon Sanderson any more?
So I understand you are arguing that derived works should not be subject to royalties, i.e. I should be able to produce a film based entirely on the work of a living author without restriction or the need to pay any royalties.
No, you're over-generalizing what I'm saying (a.k.a. straw man fallacy).
If you're commercializing e.g. goodies that use the exact same character designed by some artist, so that anybody can tell you it's the same, AND if the traits of this character are actually original (not just so that anybody would come up with it independently), AND if the people buying your goodies are all thinking about the original character in the first place, AND if the original author is alive, then I'd absolutely agree that royalties need to be paid.
That's just an example. To tell you that in specific cases it's obvious that royalties are required.
But in the general case, no. Because, else, anything just is a derived work. Just think about it.
It's even impossible to retrace all of the woven threads, ramified tendrils, that link your mind to the billions of other minds all over the world and over the ages.
The world of ideas is liquid. All is mixing, all dissolves and disappears in everything else, and is reborn new and different, again and again.