You'll see less semi-final blowouts with an expanded playoff.
By going to 12 & giving the top 4 byes, the Cincinnatis & Michigan's would've been weeded out in the quarterfinals.
The predicament that the playoff currently has is: do they take the 4 best teams or 4 most deserving teams?
By going to 12, you get both. The most deserving Cincy & Michigan, get in while the other teams that are likely better than those two teams also get in.
Expanding the playoff is the right things to do.
1. Creates more meaningful regulars season games in Oct & Nov
2. Gets more teams & fan bases involved in the race, which is good for college football.
3. Creates more good playoff matchups when 12 travels to 5, 11 travels to 6, etc in the 1st round
4. Weeds out the deserving but not good teams that typically create these bad semi-final games while still giving those teams a chance.