and i'll give you a reason. national interests. it's simple as that, any realist can confirm that line of thought.
any government that is in the position the US is in is going to look to do what it can to keep that position. the best method to do that is to have influence in every region of the globe. sort of like an empire, but not quite the same physical thing.
its a double edged sword too. moving in and installing a new government to create strong bonding for the future usually creates a mess in the beginning. with the way the media reports these days, all mistakes are highlighted and everything that goes right is completely ignored, because positive news doesn't sell. the government needs to create a new socialist-like doctrine of not allowing corporate media networks into the country to broadcast war coverage. it's destroying morale across the country. it's a continued degradation that will never change for the lighter.
and entry into the war was based on faulty information, no one knew it at the time. but once we got started and it was proved false, we couldn't possibly pull out. we had and still do have reasoning to have stayed and to oust their leader.
why not cite your favorite little b!tch clinton (bill) and the numerous times he had operations sent to Iraq, and failed at their duties. he used the true power of presidency and never fought for a declaration of war, instead merely used his ability for a 90day troop deployment.
oh, thats right.. because you'd rather use every reason you can to justify your uninformed hatred of Bush. it can be reasonable to dislike a sitting president for economic and other stateside reasons, however for war actions.
and all these situations can also be avoided if the UN wasn't the pansy-a$$ organization that it is. to truly govern the world, it needs to have sovereign abilities, and merely placing sanctions on a country isn't likely to control it much. look to Korea's recent actions for this. sanctions do jack-sh!t in the real world.