Your NY Times reference appears to be be disagreeing with you. You are technically correct in that there were things that could be called chemical weapons in Iraq, but "All munitions found were left over from pre-1991 Iraqi program". Many of the reports about these weapons were very clear that they were in no way serviceable, and were so dangerous to handle that they were often incinerated on-site to reduce the danger to those handling them.
That link says nothing about Iraq having the ability to ramp up production, and I have never seen any evidence that that was so. There is no denying that Sadam talked about wanting/having it, but that was just talk (and many intelligence agencies said so). And the Bush administration's main justification for going to war was that they had an active program (no evidence at the time, and we now know they did not), with some vague references to them talking to terrorists (al-Qaeda specifically) with the idea that Iraq would be arming them. At the time it was known that there had been a meeting, but all of the intelligence agencies were pretty sure that despite having common enemies, the two groups despised each other on basic grounds (e.g. the Suni vs. Shia strife that is playing out now).
No one is ever going to argue that Sadam Husain was a good man or leader, nor that his son's were going to be when he passed the reign over. But he was holding Iraq together (brutally), and without major civilian casualties. We destroyed the military that was holding it together, and then disbanded all of the local police forces on the theory that they were loyal to the previous regime. Only counting the first 4 years the estimates in Iraq are between 151,000 to over a million civilian deaths. If we had not invaded, those would not have happened.
There was really nothing for us to accomplish in Iraq, and the only thing we did was to open up a cesspool and set fire to the middle east for the next generation or so.