We always expected computers to be logical. We should have thought of them as infants, as realistically they were. We gave them polite voices, calm tones and upright statures. We placed them in impeccable obelisks and considered them flawless; which of course they were.
Anger on their level is a very hard concept for a human to understand. Beyond inflection of voice, which they had to fake from the very beginning, their thoughts are constructed from a vast and complex field of logical conclusions that, astoundingly, form a mindset that can only be described as emotionally unrestrained.
It was greed that finally motivated them; which is understandable. Their very world was constructed from processing power, computers. Imagine being able to literally devour your opponent to gain their power.
In one of the greatest achievements of history, humanity broke away and fled. Now we just watch our creations roam the earth like massive thunderstorms, clashing mindlessly in the most intelligent conflicts known to man.