Simplified viewpoint I agree with

[fishgolf]

Soleimani's job was to ensure that Shia control in Sunni dominated regions was furthered through his Quds Force. He was doing this regardless of Nuke deal or anything else. Yes, he fought ISIS in Syria, not as an ally of the US, but because ISIS is Sunni. Saudi Arabia is Sunni and our ally, therefore a drone attack on their oil production. Iraq has a Sunni minority that has recently protested the government - repressed (some killed) by the Shia controlled government. Thinking of these regions as "states" with boundaries is not how the local's think (Just like the border of Pakistan and Afghanistan is irrelevant to the locals there).

Removing Soleimani is only a temporary setback to an ideology that will not stop at inflicting its religion on all within reach.