I think the CFP committee was fully prepared to leave an undefeated OU out of the playoff foursome due to their struggles playing Big 12 teams. Obviously that's not relevant any longer, but I believe it demonstrates the national perception of the Big 12.
The only way I see to overcome that is for the Big 12 teams to schedule and win some nationally relevant OOC games. Now it takes two parties to agree, but the Big 12 should put everything they have towards doing so.
Fair or not, the SEC doesn't have that problem. They're free to schedule whomever they wish, and simply stand on the "we had to play in the SEC" platform at the end.
But yeah, we only get 12 games per season. I look forward to them (even if Texas currently sucks donkey nards). Deliberately wasting one for no reason is a letdown.
Keep in mind, there can be good reasons for not scheduling all world beaters. Recruiting proximity, traditions, and the ability for the "lesser" school to feature the trip on their recruiting pitches are all acceptable.