The last thing I want to have when using a bayonet is a loud scream... In FH2 they are supposed to be silent weapons, used when you are sneaking upon an unsuspecting enemy, alone at an enemy flag, commando style...
Besides, if you want screaming while stabbing there's always the "CHARGE" button on the commo-rose...
The fact is that a bayonet charge could never actually work in FH 2... There are a few reasons...
1. A charge is not made of one lonely man
2. If you are charging, you run at the enemy, the soldiers in FH 2 don't actually have a running speed anymore, it's just a bit faster jog
3. You can't shoot with your bayonet on, making you extremely weak in medium range...
Now, the only way a bayonet charge could work would have to have these issues resolved...
The first one is easy, all it needs is a willing squad (but nobody is willing to do it if he knows it's bloody pointless).
The second one is a bit harder to solve, ideally there would be a way to run faster while having the bayonet attached... Don't think that's possible in the engine (maybe make rifleman class run faster?).
The third one... Well we all know it's an engine issue...
The only way I could see that work would be if you could somehow keep your bayonet attached and simply switch to it, without the animation (sort of like how it works in Mount and Blade, you press X to switch to melee mode). But that would be ridiculous if everyone had their bayonets on all the time...
So ideally in close quarter maps, and maps where it's historically plausible there should be some kits with bayonets permanently attached... (those that come to mind are Tunis, Giarabub, Ramelle etc.) So you don't lose time on the animation and can stab right away.