Texas and OU like this format because it allows them the easiest route. Their game b/t each other is minimized in terms of conference importance. A loss or a win in that game doesn’t nearly always determine your eventual fate. Divisions are good for the conference, a round robin is good for OU and Texas. This conference is not about the collective good.
I agree with you, but here is the problem, going forward, for Oklahoma and Texas.
Oklahoma is not going to be an SEC candidate because they have, somehow, bound themselves to Oklahoma State. That may not always be the case, but it is for now. The SEC was interested in OU, but was not interested in OU + OSU. The Big Ten already said, "No," to OU. The Pac-12 may still be there, but again, they didn't want OU + OSU, and they made it clear that any expansion without Texas wasn't worth it to them.
In regards to Texas, they do not want the SEC, the Pac-12 no longer wants them (I guess they burned a ton of bridges), and the Big Ten is kind of a horrible fit. Also, the state of Texas was cool with A&M splitting as long as A) the Big 12 didn't break up, and B) other Texas schools benefited from it. Both of those things happened, and if you're a fan of TCU, and to a lesser extent, SMU and Houston, what happened last year was a massive improvement. Any movement by Texas, now, could put all of the other schools at risk. The legislature will shoot that down.
What is good for Texas and Oklahoma is a strong conference. They can treat this like their own personal fiefdom and watch this conference turn into North Korea, or they can be like Alabama and Florida and help promote the brand.
Texas is always going to make more money than God. What they need to do is be the kingpin of a (perceived) strong conference. That's what's missing.
Expansion allows that to happen.