"A little flat footed"? It is called the will to win, they (Fallujahn insurgency) have it, we (civilian leadership) don't.
There was more to the apparent early leashing of Marines in the early weeks than just a lack of political will. Their “misunderestimation” was explained pretty well in #63 here and more in #137 here But I agree that after a couple of weeks of massive Iraqi casualties, politicians imposed overwhelming pressure leading to a poor military decision.