The U.S didn't go to war because Bush said "hey, let's send freedom on the march, baby!" It went to war on the pack of lies that Iraq was building WMD's (a lie) and had connection to terrorists like AQ (also a lie) Tied into the whole thing there was the insinuation that the Iraq war was somehow tied to 9/11, which if that terrible and unforgivable event had never happened they never would have garnered the popular support necessary to go and invade other countries. Interestingly enough, for all the tough talk about the "war on terror" and fighting the terrorists "over there so we don't have to fight them over here" The fact remains that the majority of the hi-jackers on 9/11 were all Saudis, and Saudi Arabia is one country that has done nothing but profit since the U.S went into Iraq. Coincidentally there is much media reporting about Iran providing weapons to Shia militias but very little about weapons being provided to various Sunni groups from Saudi Arabia. Wouldn't want to talk badly about an ally now, would we? Oh yeah, and whatever happened to that Osama guy (also a Saudi national)? Seeing as he was responsible for 9/11, shouldn't the U.S have thrown everything in their disposal at him until they caught him?
Let's examine the logic of this situation.
U.S is attacked on 9/11. It is determined shortly after that the culprit is AQ led by OBL. So, send some bombers and a few thousand troops (and a bunch of pallets of money to pay the northern alliance to fight a great deal of the war) over to Afghanistan, and drop in plenty of those cool scary looking specops guys to go hunt him down. Apparently they got real close, and then he got away. Oh, too bad so sad. We'll keep looking for him though, honest (six years later)
THEN, it's time for the real show. OBL and his group AQ may have killed thousands of American citizens but now Iraq is the real threat! They have WMD's and even have mobile chemical weapons labs. We can't let our smoking gun come in the form of the mushroom cloud. Rumour even had it, that Iraq had obtained yellowcake uranium from Nigeria (didn't you hear?!?) And we could say with confidence that Saddam was plotting to strike within America. So, gather up hundreds of thousands of troops, six (was it six?) aircraft carrier groups not too mention a whole wack of other ships and sit them on the border and off the coasts. Of course they're not their to invade Iraq! We just spent billions to send them over there to intimidate Saddam into complying with UN weapons inspectors (although those very same inspectors said time and again they were confident Iraq had no WMD's which proved to be true)
Iraq was never a threat to the U.S, and massive amounts of manpower and materiel were expended going after it while the real perpetrators were largely left alone. AQ wasn't in Iraq until after the U.S invaded, because they WANT to be there. The U.S invasion of Iraq is precisely what Osama Bin Laden wanted, and even stated that it was his goal several years earlier to provoke the U.S into invading an arab country. The subsequent past 4 and a half years have provided AQ with previously unimagined recruiting opportunities, both in Iraq and around the world. In invading Iraq, the U.S has actually succeeded in making various terrorist groups stronger and more defined than they ever thought they could be. Now, the average joes in Iraq have had enough of AQ's terror and are starting to wipe out the slimy SOB's, and good on'em for it! The point is the entire thing was needless, and never had to happen. The Iraq war is a war of choice, it is illegal and has tarnished the reputation of the good American people around the world.