Dead authors don't get money for new books. If people are buying the books, who gets the money? Assets have value dictated by their money generation over time. Assets can also be owned by companies. Should the a book owned by a company suddenly be out of copywrite because the author dies? Should a movie made by hundreds of people be free at some point when the writer or director dies?
Should a house be open to the public after the owner dies? Should it go to some government?
There isn't any sort of consistent logic here. Once you think about assets, companies, multiple people working on something etc, it will never make sense to think someone dying means all their work should be free unless they own it and make it free in their will.
Houses are rivalrous goods. The whole reason IP is treated differently is that it's non-rivalrous. One theatrical company doing a production of Macbeth does not stop another. One orchestra performing a Mozart concert does not stop another. There isn't a consistent logic between rivalrous real and personal property and non-rivalrous intellectual property precisely because they're different things.
The right to legally enforcable exclusivity in intellectual property regimes like copyright or patents stems from a balancing exercise between incentivising the work being done (i.e. authors writing books, filmmakers producing films, drug companies researching cool life-saving medical innovations etc.) and ensuring that at some point it reaches the public domain (plus a bit of practicality).
You can say 'rivalrous' as many times as you want, but none of this explains why an IP asset should suddenly be public domain when someone dies. You didn't answer any of the questions about various scenarios like company ownership or lots of people being involved in something's creation.
Also there are already time limits for things to be in the public domain and medicine patents expire and become public domain, so I'm not sure what your point is.
Should a house be open to the public after the owner dies? Should it go to some government?
There isn't any sort of consistent logic here. Once you think about assets, companies, multiple people working on something etc, it will never make sense to think someone dying means all their work should be free unless they own it and make it free in their will.