you forget some of the polls do not use margin of victory. I believe a lot of them changed how that was used because to many schools ( for example OU) like to run up the points on everyone they play. It makes the running up the score worthless in the rankings. And that is also why they take an average of the 6.
That being said I agree we need a play off system so schools do not get screwed up of the chance for the National championship.
while margin of victory may not be an official part of the polls, the score does leave an impression in the minds of voters whether you like it or not