Your argument is extremely flawed.
What if USC and Ohio State start the year 1-2 and both go undefeated, beating three ranked teams each? Meanwhile, an SEC team, say Florida or Alabama, also goes undefeated, and beats five ranked teams? Are you saying you'd be happy with the SEC Champion getting left out in this scenario?
The national champion should not be decided with a preseason poll. I honestly don't think there should be any polls until at least the third week to keep teams from having a pre-set advantage.
What if the team that starts the season #1 loses their third game and drops a few spots but stays above an undefeated team that started the season outside the Top 25? Are you saying that undefeated team should have no chance of passing the 1-loss team if the 1-loss team wins out, just because they started the year far behind them?