I haven't read all the posts yet, but want to answer based on the question before reading. I'm sure this has been said, or something like it.
Hate is an emotion. We come equipped with the ability, but I think we have romanticized hate the way we romanticize love.
But if it is part of our makeup, there is likely a benefit to it. Unfortunately, it is taken to levels that are hurtful to others and the person hating. Perhaps it is some kind of warning system we have----like hating an abuser will help us to protect ourselves----because honestly, love is something that really complicates the abuse issue. A friend of mine witnessed a man backhand his girlfriend. He said he heaved a heavy sigh, because he could not watch that happening, yet he also knew if he stepped in, the woman would likely attack him because of this love. But he had to do what he had to do, so he stepped in, not with threats of violence, but simply firmly to tell the man that he could not stand by and watch this happen. And the woman started screaming at my friend to leave her boyfriend alone. My friend stayed calm, as he expected this reaction, and simply insisted that he would not stand by while one person hit another, and please stop.
I've had a lot of friends who were police, and they say the same thing. They get a domestic violence call, generally a man beating a woman, but not always, and when they step in to make the arrest, they prepare themselves for the woman to come at them.
What is this? Is this the obligation we have been taught to never hate and always love? It does seem twisted, and therefore the results are twisted.
I have not hated many people in my life. But there are a couple who have proven to be so dangerous to my body and my psyche, that hate is the appropriate sentiment if it keeps me from allowing them back in to do their damage. People have tried to make me feel guilty for hating, but it is an emotion with a purpose. This silly notion that we should love everyone just doesn't make sense. There are some people who should repulse us, and I believe for good reason. Otherwise, we get this weird and disfunctional mixture of love/hate that leads to strange situations.
Unfortunately, hate is an emotion that is easily manipulated, and that leads to some horrible things. I'm not in favor of that. But LOVE is also an emotion that is easily manipulated, and it too can lead to some awful things.
JW's don't 'hate' people they shun (as a rule) but they 'love' the organization, the people, and the god who said they must shun. So OUT OF LOVE, they do disgusting things.
Any emotions manipulated and used for some purpose are bad things. In their natural state, I'm not so sure.