When was the last time gas masks were really needed? WW1? I’d take my chances.
The potential was very real in Operation Iraqi Freedom, and a lot of folks spent time in MOPP gear.
Then there were things like this:
Casualties of Iraq’s Abandoned Chemical Weapons
http://www.nytimes.com/interactive/2014/10/14/world/middleeast/us-casualties-of-iraq-chemical-weapons.html
Abandoning proper NBC abilities would be very foolish for a moron military.