If hate is so bad, how come it gives great results with (good) metal music? Maybe there's a noble hatred closer to love and determination instead of the corrupted ego driven hatred of mallcore.
Very good question. I am glad you present it.
I blame vocabulary. Like "love", hate is one of those words that is applied too liberally; this results in diluted meaning. In my experience, love and hate in their purest forms are not just two sides of a coin, but the same motivating principle. Sort of in the same way we feel satisfied after a good fuck or a good meal. It is an intense drive to get something done, that is all.
It is different from the sort of hatred we refer to in this thread, which is a level of anger so high that it is too difficult to check and renders a person incapable of using their planning centers. Irrational and usually destructive decisions are made then. Like someone else pointed out, this reaction stems from fearfulness.
But hatred that does not stem from fearfulness is something else entirely, and is probably what you mean when talking about the hatred that inspires metal music. Good observation.