These kinds of weapons don't have to produced by a rogue nation with a "weapons program." For civilians in the U.S., Iraq was never the biggest threat from such an attack.
Saddam had a long history of supporting terrorism. Just because he wasn't the biggest threat, it doesn't mean we should have therefore ignored him.
The world community had played patty-cake with Saddam for 12 years. We finally ended that game, and showed that we will no longer accept UN games and words as a substitute for action against rogue states. And other rogue nations are now on notice as a result.