One important reason for why to get military control over oil-producing countries like Iraq and Libya is to stunt their economic growth. Why? Because otherwise the internal economic growth in those countries would very quickly, within a few years, given a peak oil scenario, have catastrophic consequences for the amount of oil exported from those countries.
This means that Iran may soon be attacked to prevent economic growth in that country rather than to cause a disruption of the Strait of Hormuz (which would only make a temporarily excuse for a lower global oil supply). And also Saudi Arabia may be next, with a war that destroys that country's economy and capacity for economic growth other than for the oil exporting industry. Venezuela and Brazil are other possible candidates for wars (or some severe internal conflicts or economic catastrophes).