I'm sorry, but this argument is garbage. You think this past Iron Bowl means nearly as much if Auburn's just playing for home field advantage? If they lost, they're out under the current system. With a 16 team playoff, they probably finish number 3 and very possibly get home field advantage throughout anyways. But yeah, definitely wouldn't diminish the importance of the regular season at all.
8 teams is too much. The idea of a team like 2009 Iowa getting a shot at the national title is repulsive. It's not the game we've all loved for years. And no system with auto bids could possibly avoid diminishing the importance of the regular season. Don't believe me if you don't want to, but you would eventually see big rivalry games with the starters on the bench resting up for the conference title game.