I've just come back from a WWI battlefields tour (recommended btw) and apparantly there was the issue of a ''righteous'' war at least among the milatary people. There's also the obviously mentioned next level idea, as well as the perhaps non effectiveness of the actual stuff...

On the note of Stalingrad, I believe the low temperatures have an effect on the gas' potency (something I read about in WWI gas tests on the eastern front) so it wasn't all that effective in the freezing conditions