You're dealing with split second decisions that occur in a combat zone. Do you know that even shooting a weapon out of someones hand is difficult even for the best? You seem to think Hollywood is reality when in fact it's far from it.Just saw american sniper. Why didn't he shoot the gun out of the kids hand? Or shoot near before the kid picked it up?
I'm considered very good with a handgun, I shoot an average of 260 out of 300 which means there are days I'm shooting really good and days I'm shooting terrible, there are even days where I'm shoot both very good and very bad in the same day. Everyone is like that.
The idea in war is to neutralize any threat as fast as possible, In almost every case it means killing the opponent, that's true in any life and death struggle.