The Dark side as it were, is all of the aspects of ourselves individually and collectively that we disavow. The problem is that it becomes autonomous and has a life of its own – a spirit complex if you will. If we don’t face it and transform it, we’ll project it outward onto the tribe over the hill or onto anything that threatens our worldview/identity, such as the skeptics or the believers. If we demonize our natural instincts they can possess us and we may act out their agenda as with pedophile priests. I agree there’s not much to learn from evil in itself because it’s ultimately an illusion of our creation although I think it’s imperative that we understand it. The Buddhists would agree with you: evil is really just acting out of ignorance and we need to wake up or “look up” which isn’t always so easy.