We're not talking about inheritance of real property or money, we're talking about "IP rights" or "royalties". The two are not the same. Why should someone's kid get money from their parent's book decades after it's been published? No other profession has this perk.
And, sure, why not. Let's have a 100% inheritance tax beyond a maybe a couple million in protected assets. If we want to pretend to have a meritocratic system, then we can't have that joke of a loophole creating dynastic wealth.
Either we have a system where people earn wealth on merit, or we have a feudal aristocracy with extra steps. It can't be both.
Why should someone's kid get the house from their parents decades after it's been built? The issue of inheritance is the same for physical and immaterial assets