Of course the passengers are going to take their luggage, the Chinese passengers especially, they don't do rules, they do what they want.
I'd like to see ANYONE try and take a wheeler/box of fruit/box of tea off an China mainland pax during an evacuation !!!
And besides if your passport gets burnt in the overhead bin, do you have ANY idea how much hassle US Immigration will give you? Better to have your passport , breeze through the airport and you'll be in Chinatown slurping noodles before you know it.......
Thats why I always carry my passport in my pocket.