The money in the Pac-16 is not guaranteed to be better than the renegotiated contract in the SEC. Don't you think if A&M, Texas, Oklahoma, and Ok State went to what is already the best football conference in the nation, they would get a monster television deal (more so than could be reached with a 'Pac-16')?
And Texas is concerned about money, I agree. They've built their program into one of the most successful athletic departments in the nation. When you have that much, you fear losing it; I think they look at the SEC and see one team after another that could beat them 'any given Saturday,' ruining their hopes of a championship (especially based on the way the BCS works right now). By going to the Pac-16 instead, they have a much greater chance of avoiding those losses and of being a more likely contender every year.
My hope is that in going to super-conferences, we will soon see some form of playoff system, which would lessen chance of being eliminated from contention for a championship just because you played a tough schedule and happened to lose a game or two along the way. If Texas wants a massive money deal, they should join what is already the best conference in the nation with A&M, OU, and Ok State and push for a playoff system. I don't see how the returns could get much bigger than with an SEC that added those teams.