Thanks your post tend to be rather entertaining to read as well. I'm just trying to keep in mind what my literature professor told me. Even an opinion should be backed by actual events and evidence.
That's practically verbatim what mine said as well. He's pretty fond of saying, "There may not necessarily be right or wrong answers, but any answer can be more or less supported than any other given answer."
Mengsk is one person you don't stay emperor without a system. What about those who supported Mengsk and quite possibly lost big do to his fall? Now you have a mess of ghost conditioned to be loyal to Mengsk and he's dead thanks to Jim and Kerrigan. Then there are those who lost loved ones while Kerrigan was the QoB. They are some people who will never forgive and would just be waiting for an opportunity to take revenge.
This brings up an interesting point. Even in the real world, there are what I would label "bad people" who will hurt someone they don't know to gain some kind of personal advantage. Like a mugger, for example. These people exist, and in the Starcraft universe, sometimes they're very freaking scary. Having that kind of strength, means you have that kind of strength to protect you and yours. Just because there's no immediate threat, doesn't mean you should lay aside your power.
Really, I don't see how this is much different than martial artists who train their entire lives to fight and kill, and then hope they never have to use what they know. Or someone who goes and buys a pistol for home defense, and keeps it under lock and key until it's needed. The only real difference is that Kerrigan's personal strength is considerably greater than that of a normal fighter, and Raynor is packing much more advanced tech than what is available to us in the real world.