The Big 10 has been pursuing Texas. I'd assume their plan was Texas and Notre Dame as Oklahoma doesn't fit where they want to be academically and the rest of the Big 10 schools don't really move the needle. The SEC had no problems with an Oklahoma and Texas. Not sure what Texas might have done if the Big 10 maybe looked at Texas and Kansas.
With Texas out of the picture, there isn't anyone left in the Big 12 who meet the criteria of fitting academically with the Big 10 and could increase a TV contract enough to be worth adding. What's the point to adding Colorado and Kansas if a 16 team revenue split is potentially less than a 14 team split?
With the ACC a nightmare due to their long term contract, the Pac-12 was the only logical choice for raiding and the Big 10 went out and got the best two schools and figured out how to do so without having to expand to 20 schools. Maybe long term this is all bad for college athletics but in the short term jet fuel and late nights will be a problem to contemplate while swimming in Scrooge McDuck's vault of gold coins.