I see no particular need to delete my account or any of its content, personally. I know it's everybody's own decision but frankly it strikes me as kind of needlessly destructive, like torching a restaurant because you no longer enjoy eating there. Other people still do, there's no reason to take it from them.
If Reddit evolves in such a way that I no longer find it useful or enjoy going there, I'll just stop. I'm actually happy if my old data remains useful to others - lots of times I go searching Google for information and wind up in an old Reddit thread, for example.