[pianoben]

complexity in software is invisibly-preceded with "unnecessary", and usually indicates software that is difficult to maintain or even to verify its behavior. A really cool software architecture can scratch a similar itch as a good fugue, but that's not its typical function nor is it the way we usually engage with software professionally.

Bach's complexity, incidentally, is seldom "for its own sake" - the pieces all fit together beautifully and without extraneous movement. Contrast that with some lesser works by later composers like Liszt, where you often get the sense that a given passage could be reduced or removed without harming the work.