The reason that Saddam was a massive risk to the world was because by his, and the Arab world's, reasoning, he *won* the first Gulf War. He was still in power at the end, and that meant that the whole thing was nothing but an exercise in Western lack of resolve. Another sign of weakness.
He thus became even more of a rallying point for Arab nationalism, an icon of the extemists. Living proof that the West didn't have the guts or ability to actually put fangs in their threats, to follow them to the logical conclusion.
And that, more than anything else, was why Saddam had to go. The true "shock and awe" was taking down him and his filthy regime when (in Arab cultural views) history had proved that it couldn't be done.
Anyone who thinks that wasn't a major step in the war on Islamic extremist terrorism should go learn more about the cultures that spawned it.