I used to be in the military. I have gone through the classes, and I have some understanding of military tactics, but I cannot claim to be an expert by any means.
An observation I have made, however, is often overlooked. Dynamite and machine guns. Both of these are considered "okay" in modern warfare. When they were invented, people thought they would end all war because they were so horrific. But they didn't. In the history of man, only one super-weapon has ever served as a deterrent to war. Nuclear explosives.
Why are nukes effective as a deterrent, while dynamite, fire bombs, and machine guns fall short? I believe the answer is simple. Nuclear bombs kill politicians.
The same people who are willing to put your children into the line of fire are forced to think twice before putting their own butts on the line.
Which brings me to chemical weapons. Let's compare chem warfare to other weapons. Chem weapons kill civilians, but so do many other types of weapons, including machine guns. Chem weapons are no more destructive than fire bombs, roadside bombs, anti-vehicle bombs and mines, daisy-cutter bombs, or a great favorite of mine, the AC-130 flying gun ship. Chem weapons can be targeted to kill, but they often only disable, and properly used they could temporarily disable. Still, lets consider that they are usually used to kill.
Dying from chem weapons is no more horrific than a fire bomb or a roadside bomb. Chem weapons do not stay in the environment like land mines. Chem weapons do not destroy buildings and hospitals. Properly equipped, troops can move through chem weapon areas in relative safety. Chem weapons disperse usually in hours, weeks at the very worst. If your goal is to defeat an enemy quickly, I cannot imagine a better weapon.
Chem weapons would also be a threat to the lives of the elite politicians who run the wars. Could this be the reason they are banned?
I do not love war. I do not want war. I would never advocate bombing anyone. But in a real war--like the one in Afghanistan, don't chemical weapons make sense? Do you think Al Queda would hold back if they had chem weapons?