Pre-2000's can't really be compared because the rules were not as offense friendly. Defense won championships and run first, ball control offenses prevailed.
Post-2000 the league became more pass oriented as rule changes began favoring passing and scoring.
Cook has been phenomenal and should be a focal point of this offense. However, I don't believe that's why our offense is so run heavy focused. If the reason was Cook, he'd be getting the ball 20-25 times a games. I believe McDermott is trying to cover for his defense by having a run first, ball control offense. Even when we pass, it's quick hitting bubble screens, short passes that are an extension of the run game. McDermott does not want a quick strike offense that is constantly putting the defense back on the field because he knows they can't hold the best teams, ie: 13 seconds, etc...