Pushed to the limit
Everyone thought USC was better than Texas back in 2005. Even USC thought they were better. Matt Leinart continued to think USC was better even after the game was over.While I'm pretty sure UT will handle Nebraska, they will be the under-dog regardless of who they meet. The Big 12 has gotten very little credit this year, just as they have for several years. Maybe Florida and 'Bama are both better than Texas, but I would like to see the proof.
As far as non-UT fans not wanting to see them win, I still think it would bring some validity to the Big 12 as a whole. I felt like OU was going to win last year, and it would have given UT a little more credence.
Florida and Bama may be better than Texas in a lot of publications and on a lot of talk shows but like you said, they will need to prove it just like Texas will have to prove that they are better than Nebraska.