It's an important issue in at least two respects. First, and most important, we have destroyed Saddam's government's capacity to use, or threaten to use, these WMDs, either directly or through other terrorist organizations (his government already qualifying as such itself). Second, to the extent that WMDs did exist but were destroyed just before the war began (as some evidence suggests), or still exist and are hidden, we need to track them down and secure them so that these weapons or their precursors don't ultimately end up in the wrong hands.
I am just saying that I don't care if they didn't have them. But I DO believe they had them. I do believe they will turn up. If they don't surface, but they find evidence they were destroyed...fine with me. The correct course of action was still taken.