Couple of thoughts, invite discussion.
1) When I got to my first duty assignment, first thing I bought was a knife. The next day, there was a battalion barracks search for knives. "Rambo" style knives were confiscated, and we were told that knives with saw serrations on the back violated the Geneva Convention, since they could cut bone. Sounded like hooey to me.
2) Bayonets tend to be dull, since a cut with a sharp knife tends to heal better, and a dull one "tears", making a jagged, nasty wound.
3) Best knife I had while I was in was essentially a modified bayonet that I had some custom work done on. Indestructible. When I left, gave it to my buddy. What an idiotic move, as I've yet to find this knife's match.
4) For me, at least, the bayonet course was the roughest and scariest part of boot camp. As close as you can come to true barbarism in training. God, I miss it.