I can't comment on Gow or Transformers. However, name ONE situation in MW 1/2, where someone who get's close enough to make use of his knife, and has the time for the animation to finish, could not have just fried your ass with a shotgun or capped you in your head three times?
If you get knifed, it's due to one of these reasons:
a) You didn't see the attacker coming (he could have just shot you)
b) You saw the attacker running up to you, but missed him (he could have shot you)
c) You missed the opportunity to duck under the knife, and in return melee him, since it has a cooldown.
d) The attacker lay in hiding somewhere, waiting for victims. You failed to notice him. (He could have shot you, or placed a clay)
e) You failed to end a firefight quickly, but let him close in / did it yourself, and failed to use your own knife.
Know what all these situations have in common? In none of them, you died due to balance issues. The main reason, besides being a close combat option, if ammo runs short, for the developers to include the knives, is well phrased: [...] to use your knife, for a fast and humiliating kill. And indeed, it sucks, if your armed to the teeth, and someone proves, he doesn't even need ammo to dispose of you. That however, is NOT the games fault.
Now before you start hating on me:
I am by no means perfect at cod, I still loose to my boyfriend all the time, and there's days, where I have a hard time maintaining a 1:1 K:d ratio. BUT: Dying is part of a online shooter experience. Get better and you'll die less, but even the best die eventually. If you can't handle that, there's always singleplayer with cheats turned on.
(Also, please forgive me for sounding a little agressive, I'm just sick of people making excuses)