I think the people of Fallujah (still poisoned with depleted uranium) and the torture victims of Abu Garib would beg to differ with you.
The fact that if you ask probably >85% of voting Americans if the Iraq War was a good decision -- they would say no. And they vote with that moving forward.
It's an imperfect system that is still the best available.
Yet you bring forth these US atrocities in war, while Saddam himself killed 10's of thousands of innocents with gas etc. Directed from the top.
That's the kind of stuff that would happen in a power vacuum where your autocrats take control.