What I am trying to say is that both things are very different in details where it matters, so I think this is a rather flawed analogy.
Maybe a closer analogy would be landowners who rent out land. Should a person who bought land 10 years ago be able to generate revenue from renting it to a farmer?
But even if this would destroy your business model, that doesn't mean it would not be a good idea for society as a whole. Business models become obsolete all the time. If there is enough demand for your software, you will be able to fund the development of it even without might-as-well-be-perpetual exclusive control.
In that case, the value of land is created entirely by property law.
A farmer has the exclusive right to land from the existing fixed supply that the entire world has available to it. He didn't create it and no one else can use it. Whereas a software developer makes something new. Nobody else was deprived of anything pre-existing. Less justification for taking code from a developer than land from a farmer.