Removing Saddam was a necessity and the fact that US troops did not have to face the use of Weapons of Mass Destruction in their invasion to remove Saddam from power is something that should be celebrated!
If removing Saddam was a necessity regardless after the unanimous passage of UNSC Resolution 1441 and the subsequent UN inspections that transpired as a result of that Resolution, then you are supporting the argument that Bush lied in October 2002 when he asked Congress to authorize the use of force in order to compel Saddam Hussein to allow UN inspectors back in.
You can't have it both ways. Bush did not seek regime change for regime change's sake in October 2002. The intent of the authorization by Congress for war according to the language in the AUMF was only if necessary had Saddam Hussein not allowed a resumption of UN inspections as he did.
In fact Saddam Hussein offered Bush in December 2002 to let the CIA come into Iraq to search for WMD alongside UN inspectors. Bush rejected that offer.
Saddam kept allowing inspectors back in then sabotaging their ability to do their job by refusing them access to various locations. In other words Saddam was the one doing the lying when he claimed to be letting them in when he actually wasn't.