I have no idea if we "should" have tried to liberate Iraq or not, but my experience after 2 tours was that like everywhere else, 10% of the people are 90% of the problem. I can't count how many times I was tipped off to IEDs due to the Iraqi kids. The adults were generally scared shïtless of the extremists and that is why they often were reluctant to help us. It was out of fear of reprisal, not because they hated us. Their entire families would be killed by the Mujahideen/ISIS/Al-Qaeda in Iraq if they were seen cooperating with us. The general populace (at least in Al Anbar) wasn't overall against the MNF-W occupation, though they were (rightfully so) leery of it and its effects. They knew once we withdrew the extremists would take right back over.
The islamic society concerning women, religion and what they perceive as right and wrong is completely screwed up and they just simply don't know any other way. I won't disagree with that but they're not all bad people there. Far from it.
