Texas and OU don't make the conference stronger... in fact, they water it down.
Texas hasn't been good in a long time.
OU has won their conference a lot recently and made it to the CFP, only to get waxed. They are the only Big12 team to make the CFP, and haven't won a game.
Last year, Iowa St. won the Big12 regular season.
Last year, the ACC put 2 schools in the CFP, the SEC put 1. That would have been the same if Texas and OU were in the SEC. And that CFP money would have been split between more schools.
They are big schools with big fan bases, but they do not enhance the quality of play in the SEC.
They put a bigger strain on the travel budgets of non-revenue sports, and make everyone get to play cross-division opponents even less often.
probably an unpopular opinion but as usual, I'm right