It was about giving US companies control over the profits from the oil industry and crushing an unaligned country in the region to turn it into a US puppet state, not just to carry barrels of crude oil home.
dont forget that Iraq _was_ a US puppet state for the bulk of the Iran-Iraq war. It's entirely plausible that Hussein just got too uppity, and needed to be taken out.
Also line up the pockets of the military contractors that got paid to "rebuild" Iraq.