The usual steelman I hear is that Ulysses S. Grant wrote his memoirs on his deathbed because he knew the royalties after he died would take care of his family. I grant that's a marginal case but I don't know that the CBA there actually works on long copyright's side.

Taking copyright away on death is a bad method, and that's a reasonable argument against it.

It should be a fixed term that isn't very long. And if that term ends before death and they want more money then great, write something new.

I think most people objecting to copyright lasting after death are really reacting to how long it all is, and the average amount of time that is. Some of them really don't want it to go past death, but I think most of those objectors would be fine with copyright that lasts exactly 25 years no matter what.

you dont need copyright for that. by the time he died the family could have kept the memoirs and sold the exploitation rights to whoever wanted them. contracts are a thing.

Exactly where do "exploitation rights" come from if not copyright? Anyone who is going to enter a contract for these "exploitation rights" is going to want exclusive rights so others can't just share, republish, copy, etc. This is what copyright affords those who want to sell "exploitation rights"

lets say a publisher secures the manuscript after buying it and the copyright is gone at the author's death. As a first mover they will make most of the money during the first publishing round. By the time copycats end up on the market most of the market for the book was captured by the first mover.

That's more of an argument for making the duration fixed and not dependent on the authors life at all. Having both lifelong copyrights PLUS a fixed duration is just double dipping.