Ok, here is my personal experience with firearms and military training... I generally dislike these personal accounts, because you dont know me, and there is no way to know if it is true... anyway
In my training I was never taught how to use a knife. The only reason we were taught to use a bayonette was for what is called "Agression training". They give you a bayonetted M1 and tell you run up to the dummy, scream and stab it. The only purpose of the excercise was to make sure you would be able to kill a person when it came down to it, not to train with a bladed weapon. At first it feels weird since you have never stabbed someone, you keep trying to stop yourself short, but after awhile you dont think twice about shooting man targets, or stabbing them.
If I had ever tried to run in swinging my gun in an excercise, I think my Top would have kicked my butt. That is defeating the entire advantage of the US military. We have powerful long range guns, grenades to clear out rooms or trenches, and powerful support vehicles. Even if I ran out of ammo and people were charging me, I would either pull out my sidearm (I can pull a trigger much faster than swinging any weapon) or retreat. What is the point of giving up my advantage in long range combat?
I came to the conclusion after awhile that they dont teach you how to effetivly use a knife is because they dont want you to use one. Just like how officers in command usually dont carry rifles (only a pistol). They dont want them to concentrate on shooting people, they want them to give orders. The pistol gives them some self protection, but only as a last resort.