The War in Iraq was a war of choice on the part of Bush and his hawkish cabinet, it was an unnecessary war because those who attacked New York on 9/11 weren't trained or supported by the Iraqi dictatorship, they were trained and supported by the Al-Qaeda training camps in Taliban ruled Afghanistan.
Our aims should have been to destroy the terrorist infrastructure in Afghanistan, secure and defend US or Western borders and use our intelligence/special forces to counter terrorist activity. Iraq was not part of our need to punish the 9/11 attackers or to combat terrorism, it was W. doing what daddy didn't finish.
As for Iraq being like terrorist flypaper, maybe it was initially successful, but terrorists don't need Iraq they have Pakistan, Yemen and perhaps even Bosnia. Now we have liberals, military leaders and diplomats ready to raise the white flag to the Taliban and buy them off, liberal war weariness is the cancer of intelligent combat strategy.