To macreverie,
True a rifle used as a club would be an instant incapacitation... if you landed the hit. It does require more of a wind up than a bayonet stab and therefore could give your opponent a chance to see it coming/dodge the blow. Now think if you are in a somewhat thick melee or fighting in a dense forest, you lose the ability to wind your rifle back. If you're not careful with the back swing, you oculd kill your own man or destroy your rifle on a tree. In these instanes I would say the bayonet is more practical due to the ease of wielding. Also, I have read many accounts where soldiers used their rifle as a club, but at the expense of their rifle. The stock simply shattered on imapact. That's another interesting factor. You could wind up making your rifle a "one hit wonder"

. My final conclusion would be that they used it all. I think they used whatever was best in any given situation, or at the very least, what they felt was best. Whether that be a rifle, bayonet, knife, rock, or fist, they used them.
Although originally, I didn't think the question was whether or not the club or bayonet was a better weapon. The question was whether or not the bayonet was obsolete. I would have to say it was not, given its extremely wide use(with great effect) in the Civil War. Also, my grandpa that fought in World War II defended against several enemy bayonet charges and participated in them himself. So I would have to say that if both sides were still using bayonet charges in World War II, they had to accomplish something.
To Ajhall,
I think that's a shame. I think every soldier should be trained with the bayonet. Hand to hand combat is ALWAYS a possibility, no matter how good our weapons are. I think that if it comes down to it, not training with the bayonet could get some of our soldiers killed. But we all know that the U.S. Army knows best in its infinite wisdom... right?