It is not good to simply forget the past and ignore the intentional deceptions being made about it. The aim of these deceptions is to cause division not find a solution.
You're right. The President didn't make 9-11 or Al Qaeda centerpieces for invading Iraq. But its no myth, WMD were the major reason behind PresBush ultimately ordering the invasion of Iraq, or as you say "the centerpiece" for war.
You need to go back and read the speeches Bush, Cheney and others gave prior to Operation Iraqi Freedom being undertaken. Example. More then half of Bush`s speech to the UN on September.12,2002 was aimed at Saddam Hussein and his WMD programs. A few snippets.
"In cells and camps, terrorists are plotting further destruction, and building new bases for their war against civilization. And our greatest fear is that terrorists will find a shortcut to their mad ambitions when an outlaw regime supplies them with the technologies to kill on a massive scale.
In one place -- in one regime -- we find all these dangers, in their most lethal and aggressive forms, exactly the kind of aggressive threat the United Nations was born to confront.
"... Saddam Hussein's regime is a grave and gathering danger.
"... Saddam Hussein has defied all these efforts and continues to develop weapons of mass destruction."
Here's another example.
"Our mission is clear in Iraq. Should we have to go in, our mission is very clear: disarmament."
--- PresBush, March.6,2003
I don't think the President could have been more clear. There were other reasons for invading Iraq. Saddam thumbing his nose at endless UN resolutions. Oppression of the Iraqi people. Keeping a free flow of oil from Iraq. Removing a haven for terrorists. But the WMD issue was the premier issue for Bush invading Iraq. As it turned out, WMD were found, just not in the quantities that were anticipated. Human Events recently gave this account of WMD found in Iraq.
Found: 1.77 metric tons of enriched uranium
Found: 1,500 gallons of chemical weapons
Found: Roadside bomb loaded with sarin gas
Found: 1,000 radioactive materials--ideal for radioactive dirty bombs
Found: 17 chemical warheads--some containing cyclosarin, a nerve agent five times more powerful than sarin
"The dictator of Iraq and his weapons of mass destruction are a threat to the security of free nations. He is a danger to his neighbors. He's a sponsor of terrorism. He's an obstacle to progress in the Middle East. For decades he has been the cruel, cruel oppressor of the Iraq people."
--- PresBush 3-16-2003, Azores Portugal
"My fellow citizens, events in Iraq have now reached the final days of decision. For more than a decade, the United States and other nations have pursued patient and honorable efforts to disarm the Iraqi regime without war. That regime pledged to reveal and destroy all its weapons of mass destruction as a condition for ending the Persian Gulf War in 1991."
"The danger is clear: using chemical, biological or, one day, nuclear weapons, obtained with the help of Iraq, the terrorists could fulfill their stated ambitions and kill thousands or hundreds of thousands of innocent people in our country, or any other."
--- PresBush 3-17-2003, Address to the Nation
"My fellow citizens, at this hour, American and coalition forces are in the early stages of military operations to disarm Iraq, to free its people and to defend the world from grave danger."
--- PresBush 3-19-2003, Address to the Nation