Well, i say that a bullet-dodging character can still fall prey to feints and changes in the weapon's trajectory. Besides, even if the melee fighter strikes slower than a bullet (AK-102 muzzle velocity ~900mph), the blade usualy travels less of a distance than a bullet (unless the gunslinger prefers point-blank shots).

As for impentrebale armor - i hope that none of your forgot that armor has a tendency to break after enough of force is applied? Nothing is stopping us from having characters that dual-wield full-auto anti-tank rifles with several hundred rounds to spare.