This is true. QB's whose running is their best (or only) quality just don't win Super Bowls. Runners (like Staubach, Elway or Bradshaw) eventually have to settle down and become pocket passers. They use their running ability to be elusive if the pocket breaks down. But they don't just take off at the slightest provocation.
Michael Vick is a phenomenon. He's like Deion Sanders throwing the ball. If anyone could run their team to victory, it's him. But I predict even he'll have to become a pocket passer before its all said and done.