Many authors would love for their heirs and assigns to be paid in perpetuity. They'd probably love a lot of things. That doesn't mean society is obligated to give those things to them.
My initial "snark" is a statement that J.R.R. Tolkien didn't create his works under the ridiculous copyright regime we have now.
That's an argument, to me, against the "necessity" of this regime. It serves to show that this regime is rent seeking, a windfall for existing copyright holders, and an impediment to competition.