If a project is abandoned and you need it, the ability to work with the code yourself (or hire it done) might mean the difference between a controlled migration

If a project is abandoned and you need it, the ability to work with the code yourself (or hire it done) might mean the difference between a controlled migration and a crash migration that would probably fail. It helps if the vendor cares, but they might not have a choice. There are plenty of ways to lose control of a copyright, from being bought out to bankruptcy.