There are other areas of the world that needed more help.
Lets take the congo for example. Roving bands of cannibalistic militia men slaughtering whole villages of people.....
OH ya...all good stuff.
There is a far more selfish reason that they went into iraq then a selfless, "help your common man" was not on their mind.
The powers to be that got that war rolling didn'tt give a rats ass about helping people or freeing them from oppression.
Its an added bonus once the war goes on. People support the war if they think that they are helping people and that they were directly threatened and it had to be done.
Very similar to Germany, 1939.
"Of course the people don't want war... That is understood. But after all, it is the leaders of the country who determine the policy, and it's always a simple matter to drag the people along whether it's a democracy, a fascist dictatorship, or a parliament, or a communist dictatorship. Voice or no voice, the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked, and denounce the pacifists for lack of patriotism and exposing the country to danger. It works the same in any country."
-- Hermann Goering, Adolf Hitler's Deputy Chief and Luftwaffe Commander, at the Nuremberg trials, 1946 from "Nuremberg Diary" by G M Gilbert.