Yes, you're probably right to an extent that Wink's Powers model is harder for humanity to swallow in some respects. Rather than blaming evil on some external extra-human personality, we'd have to confront the evil within us and between us. But Wink does also say that the Powers are more than just the sum of the parts of the material reality - that in being the inner essence of an institiution, state or system there is some extra group personality element, like when 'normal', middle class, loving fathers become football hooligans under certain circumstances.

I think you're right that the language of Satan in the Bible could be seen as a literary device, although the communities of the era of the Bible weren't literary communities per se, so more of a philosophical/narratological device - what I've said in my other comment about the 'object' signified by the signifier 'Satan' having preexistent meaning. But what was being signified by the authors/readers of the time?