And we just might do that. You put the troops, ships, and planes in the same places doing the very same things to prepare for attacks on either Iran or Iraq, due to their geographical locations and global logistics.
Plus, Iran is building a nuclear reactor and testing long range missiles. In contrast, Iraq has Word War 2 era scud V-2 missiles that have less than a 400 mile range (and Iraq doesn't have a nuclear reactor).
Frankly, we should blast Iran off this planet before taking out Iraq, especially since all we really need in Iraq is one bullet from one sniper, and poof, we've got ourselves a regime change there. Hussein is secular, after all, so once he is gone there will be no followup support.
On the other hand in Iran, their religious regime would survive the assasination of any single leader, thus making it a much better candidate for a full scale invasion.