Clinton would have attacked Afghanistan, sure. But would he have stayed in Afghanistan and/or attacked Iraq? Those are the two items that have cost dearly.
The other reason was to create a local distraction. To keep "the terrorists" occupied, their violence and attacks confined to that part of the world, and not in the US. In that sense, they "fell for it" too.
If the public need for "revenge" had been satisfied by attacking Afghanistan, I think Clinton would have stopped there. He was not a risk-taker, and he was totally driven by polls.
Bush said he had clear evidence of WMD's in Iraq, that he showed this to Blair and Blair confirmed. I think it would be fair to say that most people would agree that Hussein wanted WMD's.
So I think it's fair to think that most Americans and most in the international community believed that Iraq had WMD's. The argument was mostly over whether an invasion was an appropriate response.
It was only "crazies" who believed both that Bush lied and that he was able to either snooker Blair or convince him to join in the lie.
Sometimes the crazies are right, though.
The television was always sure that the war was necessary, that Powell's speech was coherent, and that the government always knows best because it has access to secret sources that it can't reveal and our best interests at heart. Of course, the television is also in the arms business.
"In London, at least 750,000 people demonstrated in what police called the city's largest demonstration ever." Source: http://www.mindfully.org/Reform/2003/Protest-Iraq-War16feb03...
But they also believed that a war was an inappropriate response to the existence of those WMD's.
Hm... "A proof is a proof. What kind of a proof? It's a proof. A proof is a proof, and when you have a good proof, it's because it's proven." - Jean Chretien, discussing what type of proof Canadian government wanted before assisting in a war with Iraq (which it ultimately did not)
Of course a (different?) large majority also believe the Earth is only around 10K years old.
So maybe selective/programmed memory is a more accurate term?
Look at http://en.wikipedia.org/wiki/2003_invasion_of_Iraq. There are lot of sources for some of the quotes that I will take here:
* "Four countries participated with troops during the initial invasion phase, which lasted from 19 March to 9 April 2003. These were the United States (148,000), United Kingdom (45,000), Australia (2,000), and Poland (194)." - So out of all the EU countries only UK and Poland went to the war.
* "The invasion of Iraq was strongly opposed by some long-standing U.S. allies, including the governments of France, Germany, New Zealand, and Canada."
* "On 15 February 2003, a month before the invasion, there were worldwide protests against the Iraq war, including a rally of three million people in Rome, which is listed in the Guinness Book of Records as the largest ever anti-war rally."