My father was a very prolific writer and he left behind a huge body of unpublished work.
Many's the dead author whose body of work has been marred by overzealous publishers or family members. If this happens to me, I vow to seek out the responsible parties and haunt them to the point of death.
But I account the use that a man should seek of the publishing of his own writings before his death, to be but an untimely anticipation of that which is proper to follow a man, and not to go along with him.
The Tolkien estate owns the writings of Professor Tolkien. 'The Hobbit' and 'The Lord of the Rings' were sold by Professor Tolkien in the late '60s, the film rights.
You want all your books to stick around after you've gone.
Hollywood would much prefer the author be dead, so that they can buy the book and do what they want to do with it.
After an author has been dead for some time, it becomes increasingly difficult for his publishers to get a new book out of him each year.