When a plumber does a job, they get paid for it in full immediately. When an author writes a book, the income comes in a trickle over an extended (but in theory fixed) time period.

If a plumber and an author were to die young, the Plumber's family have already benefited in full from the results of work the plumber did before death, because payment in full was made immediately when the work was done. What you are arguing for is that the author's family should not benefit in full from the work the author did in life. Why is that?