In a way it is kind of like a version of the Stockholm Syndrome. It is no different then when a lot of people break up from a long term relationship and think about going back. Suddenly all you can think about is the good qualities of that person and not all the bad stuff. People are patriotic towards their country so when someone invades it and throws out your leaders, you suddenly start to think that your leader was good and these invaders have no place in telling you what you should be doing.
Here is a great blog about how the tide in Iraq changed.
http://riverbendblog.blogspot.com/ the writer is a woman that lived in Baghdad and wrote this blog right from the start of the US invasion. It is interesting how she starts off hoping for good things to happen and how she had a pretty good life before the invasion and wants something like that again. Then after all the corruption and screw up things start to change. Now she is telling how people that liked us at first hate us and how people just want us to leave. She and her family actually moved because even now, years after the invasion, they don't have power and water half the time and there is no real security so they moved to Syria.