Why is the NFL considered a QB driven league?

This obsession has really only been made true by Tom Brady and Peyton Manning in our modern day game, meanwhile the formula for dominatinaly getting to and winning in Super Bowls is running and playing excellent defense. In consecutive years now rookie rushers have nearly ran their teams to the Super Bowl...like what gives? And furthermore...why does every franchise deviate from that formula even after they have a developed star QB? Until the rules change to 2 hand touch, running the ball and playing defense will always win you more games and get you closer more times than not...
So what gives??