Jeff Atwood has yet another great post on developers who tend to lock themselves away and "go dark".

I doubt there is a single developer out there who hasn't experienced this in the extreme. For me, it was when a developer delivered a "complete" feature that was so complex and over engineered that three senior developers struggled to understand what this person was trying to accomplish. The feature worked... sort of. It was almost impossible to test and completely opaque to anyone without days of reading and analysis.

In the end we rewrote the feature by refactoring what was there. The result was about 50% less code and a clean, fairly easy to understand model.

I will quote Jeff:

         "It is effectively impossible to go dark if you're practicing any form of agile software development."

For me, that fact alone fully justifies moving to an agile development process. Dealing with opaque code, whether I wrote it someone else did, is not fun.