Just a suggestion... Think through your argument before you post. There are four playoff spots and 5 power conferences. For your idea to work, something has to change. There is a thread already dedicated to that. Others will be here shortly to ridicule you and your idea...
But, your suggestion does have merit. Assuming that all 5 power conferences don't have an undefeated team it certainly makes sense.
If they do, then SOS should take effect to eliminate. Assuming, of course, that say Oregon, Baylor, LSU, OSU, and Clemson all go undefeated (I know Oregon has already lost but assuming they didn't) then Clemson gets the unfortunate distinction of being left out. They will likely have played not a single team ranked in the top 25 in the final season polls.
Still, the ranking are a whole lot of "political". While the top 10 or 15 teams are pretty well established, there is a lot of leeway in that final 5 or 10 spots to rank who they want to give a certain team more "power points" or what have you (and vice versa) and therefore a shot into the playoffs.
Your idea works about as well as the "eyeball test" that is only applied to certain teams but not to others.