I agree that in a cost-effectiveness analysis, it is difficult to defend still being in Iraq. There are other countries with WMDs, but we cannot afford to invade them too and then rebuild their country.
Originally, Iraq was meant as a warning to other countries that would build up weapons supplies and support terrorism. Libya dismantled its weapons program voluntarily. We are now trying to bring the same pressure on Iran. The difference with Saddam is that he actually did kill hundreds of thousands of his own people with WMDs. He still had WMDs in violation of the UN treaty and was developing more.
The only "lie" was perpetrated by the media in saying there were no WMDs. We are still dismantling chemical weapons that need to be disposed of in a responsible way. It's an established fact that Saddam had WMDs and would have used them. It's also thought that our intelligence has proof of more that is not public knowledge for security reasons.
I am not a shill for the Republican Party. I hate what Bush did to our economy with deficit spending. However, history will show that he saved millions of lives by reacting strongly to the threat of terrorism. We do need to finish what we started, but it is also true that we have serious problems economically that will prevent us from doing this again.