Design patents have a 15 year life. I'm a great lover of books and arts in general, but I'm not clear on why ownership rights in some creative endeavors should be massively privileged over others. Can the families of authors not write books of their own, or engage in other economic activity?
What about the families of people who toil over creative work and don't hit the jackpot? There are many fine writers/artists who never gain more than a niche audience while garbage sells big. Go to a bookstore and look at the history section, pseudo-historians like Bill O'Reilly are given more shelf space than serious historians. To be frank I almost exclusively buy from used book stores for the last decade because nonfiction offerings in chain/non-specialist bookstores are so bad. Vendors of used books tend to select for quality rather than popularity.