I Think That Would Be a good idea but what Treyarch should do is make it like Call of Duty2 Meele Meaning Smacking the enemmy twice By Clicking the right stick like all the cods
The game is primarily is to shoot your opponent, not run around like rambo swinging the knife around hoping to kill everyone in sight.
Leave it as the R3 option, it is meant to be a last resort/close quarters weapon.
Could you imagine.. Bayonet+Commando? Thats enough to make a grown man cry..