That's a scary idea you're presenting. By implication you seem to be saying that all that keeps you from going on a rampage is your ability to eliminate the emotion of hate.
Nobody lacks the occasional impulse to hate. You're deceiving yourself, either by erasing the memory of those impulses, or by having driven them deep into your subconscious where they won't trouble you (which is a dangerous place to store the volatile fluid of emotion!). In psychology, a person who is unable to experience emotion is called "affectless". The related syndrome of experiencing only partial emotion (for example, only happy but not sad; or only sad but not happy) is also considered a pathology, though a milder one. Emotions come in pairs, as you observed; you're out of balance if you experience only one half of the pair.
What I'm saying is recognized in folk wisdom. There's a bumper-sticker/poster-aphorism that I saw many years ago, by way of a definition:
stress
Controlling the uncontrollable urge to choke the living shit out of someone who really deserves it
Civilized people experience that kind of stress all the time. Sociopaths don't because they don't try to master their emotional impulses.
The murder rate in America is only about 1 in 100,000/year. Are you trying to tell me that 99,999 out of 100,000 Americans never experience hate or rage?
You cited examples of demagogues whose hate, you say, killed millions. But that's incorrect. Hate wasn't nearly as powerful an urge as ambition in the psyches of "Saddam, Hitler, Genghis Khan...Idi Amin..et al.", plus later in your essay Mao. Rather, they killed so many people indirectly by inspiring hate among their followers, and arranged their societies to remove the normal constraints on acting upon hate (well, except maybe Genghis Khan, whose barbarians weren't particularly restrained about much at all). They arranged their societies in such a way as to make expressing and acting upon hatred not just acceptable, but in fact something positive: Patriotism, defending the race or tribe, ridding the world of some evil or some villain, or just defending the charismatic ruler himself. Their various messages of hatred would have been impotent if they hadn't also removed the bonds of civilized behavior.
Ayatollah Pat Robertson preaches hate, but because he and his followers are embedded in a society which teaches people to not act upon hate, he's been unable to kill millions. His followers might enjoy the stirring of the blood they get from his message of hate, but the vast majority is unable to escape the constraints of civilization to act upon that hate.
Instead they pray to God to smite their enemies for them.
Hate is human, but hate is lower-human evolution not higher-human evolution.
...
Humanity will never eliminate hate entirely, but it will diminsh it with wisdom so that it has almost no chance to bloom and grow.
No, only another million years of evolution might eliminate hate in the human brain. In the meantime, all we can do is learn to manage it. Suppressing hate isn't managing it; you master hate by recognizing that you have a choice about whether to act upon it.