I most remember, as wagglebee stated, the primary reason that Bush and Powell kept bringing up, over and over again, was Iaq's failure to comply with U.N. resolutions; WMD came up over and over again, if I'm not mistaken, because the press kept bringing that up as "the" reason to go to war.
Yes, I remember their concern about WMD...when Powell spoke to the U.N., he had charts and pictures of trucks believed to be mobile carriers of WMD, etc.
I honestly do not remember your take on it, though you may be 100% correct.
The UN Security Council never approved of the war, so any reason given to them is no longer important. We invaded Iraq based upon PREVIOUS UN resolutions, which authorized force to enforce if necessary. The US Congress also authorized force and this WAS NOT conditional on WMDs. The United States DOES NOT require UN permission to protect our national security.