I'm not sure I agree with your thesis. Yes, we have a long history of meddling in Iran, and keeping it in check is of value to our interests in the region, as well as those of our allies in the Arab world. But this doesn't mean we don't have every legal and moral right, indeed, an obligation, to pursue Bin Ladin and dismantle Al-Quaeda and the Taliban. Afghanistan itself has little strategic value, to us, it is logistically difficult to maintain large forces there, and its borders with Iran and Pakistan are pretty remote and desolate.

The strategic value of Iraq, on the other hand, is partly due to the potential threat an American presence there presents to Iran, and for that matter, any other country Iraq borders: Turkey, Syria, Saudi, Jordan, Kuwait, the Gulf States as well as Iran. And it can be supplied by sea, through waterways we must dominate for our own survival. This is geopolitical gold, straight out of Mackinder and Mahan and Victorian Heartland theory. As for the oil, well, the spice must flow...