I'm starting to think that some of us have different definitions of it. I define hatred as the desire that someone suffer; no one should have to suffer, whether they deserve it or not (although I myself should be willing to suffer). That's why I consider it inherently wrong. An eye for an eye doesn't solve anything.
It's separate from wrath, which, in the end, boils down to disapproval. I, for one, used to hate everyone who intentionally made my life difficult/painful, then humanity in general, but then I realized that I was at fault for some of the things I hated them for (at around the time middle school began). Even though most of the things that I was aware I did wrong amounted to meek attempts to satisfy my pride (which I didn't condemn as an emotion 'til a few years later), I never hesitated to act upon hatred (or other emotions, for that matter); the only reason I ever stopped acting on it was because I deemed it either inherently wrong (at which point I refused to hate anyone, because if the desire for others to suffer isn't the epitome of evil, I don't know what is) or a waste of effort.