I do enjoy it, but as I gain more experience in building software for other people I have realized that they usually don't appreciate it. Corporate development sees this sort of activity as a liability. You can break things quite easily when you "correct" something. Poorly-written software tends to have tight coupling all over. Many parts of a system may depend on the "broken" definition of a function. Some things are just too broken to be tackled by this approach.

My current environment is much more receptive to this kind of activity, though.