I am a history major and have studied primarrily American Modern Military history and I can come up with two instances where the bayonet was used in its propper combat role. The first was in Operation Overload, LTCol Cole's Charge up Causeway Four into the occupied town of Carentan, France. First and ONLY time my grandfather, a WW2 Eagle heard the command from his officers, FIX BAYONETS! The second was in the darkest days of the Korean War. I only remember that one from a vet that told me when they went back to retake the ground one of the frozen enemy dead had a toe tag on him as well as a bayonet in his chest with the tag reading "courtisy of I company."
Now, to address the amour problem. US Marines, Army, and other combat forces are taught,, correct me here if I am wrong, please, to aim for vital points on the body. These would be the chest, head, throat, and legs. Heck, even on an ortnock, a buttstroke to his kneecap is gonna put him down. Somethign that damned big has alot fo weight on those two legs, and, with it being a joint it will be vulnerable to being stabbed or out and out clubbed.