Old chargers might be worth something to someone looking for a charger for an older cordless tool.
Some tool companies have modified the chargers mount on their newer tools, so it can be hard to find a charger that will work with older batteries, or you may need a special adapter for the charger, and parts like that are sometimes a pain to find even if their still in production.
With older tools it's also possible to replace the battery cells with newer better ones that may make the tools work better than when new.
Some older cordless tools were simply modified versions of corded models, so the build quality may be better than what is currently available.
Another thing is you should check the charger for the amperage rating on the battery end. Some European brands like Bosch made industrial quality chargers with higher amperage ratings that can charge batteries very quickly. If you happen to have one of these rapid chargers they can definitely be an improvement for older tools that use NiCd or NiMH batteries. Usually the amperage ratings at the battery terminals are 5 to 8 amps.