If Evolution is true, than hate is something that evolved in us. If Evolution favors those traits which aid in survival in a given environment, then hate is likely the "off" position of some survival light switch. Without researching it, we can assume that happiness is indicator of good circumstance, of favorable situation. Those things which inspire hate are often threats to our happiness. If we are most happy believing one thing, and we are told something to the contrary, we may feel anger and hate before we move to something more reasonable, like thoughtfulness or acceptance.
Perhaps that's it. In any situation where we are generally happy or complacent, we can describe ourselves as "surviving without immediate threat." Those things that we hate are those things that endanger this "safe" existence.
This may also be a partial explanation for why humans are creatures of habit, and get into routine so easily.
Sorry if this isn't very coherent. It was a "live" process of deduction, and I was typing as it occurred to me.