I would have to argue that point. The USA went to war in Iraq and Afganistan to find the fabled WMD and to rid these countries of Al Qaeda and Taleban influence, so we have been told, thus freeing the population from the tyranny that these organisations imposed. Obviously there was no link to Al Qaeda in Iraq, nor was there any WMD, therefore the (real) reason was to depose Saddam Hussain. Do you think that the USA intended on putting in another dictatorship in his regime's place, or a democratically elected government?
Yes, there most certainly are other dictators the US and its allies would like to take a pop at, but its not that simple; in Iraq and Afganistan there was a UN resolution that supported an invasion.
John, I cynically agree with you; Saddam was one of these dictators. Arguably his existence created an element of stability to the region and provided an antagonist to Iran, which gave the US something to smile about after the failure of Eagle Claw and the Iran Contra scandal.