> So maybe what Redis should have done is not to pull the existing rug, so to speak, but to leave it be and lay next to it a new, better rug and offer the users sitting on the old rug to move over, if they find the new features of the new rug outweigh the drawbacks of a new license.

Can you provide more specifics about your idea? It sounds like Redis would need to maintain two version. Can your ideas be implemented with the same cost structure? I doubt it.