You mean like the B1G did with Rutgers? There’s many factors beyond being good at football. UConns biggest fault is conferences see our value, but they also see us as available when needed. I would say both the B1G and ACC have buyers remorse by passing UConn over but would never publicize that opinion. Meanwhile we sit in purgatory.
You're applying Big 10 expansion criteria to the Big 12's and it's just not that easy. For the Big 10, AAU membership is (mostly) required. They were also interested in market expansion for their new BTN and got a HUGE payday when they brought in the NYC market through Rutgers. As
@noeynox pointed out above me, Rutgers football was pretty good at the time of expansion. All UConn needs to do is be"pretty good" (again) at football too.
While the Big 10 is thinking long-term (and money), the Big 12 is only thinking about football. Which candidates, if any, improve the football profile enough to continue the conference's legit access to the CFB Playoff (as it stands today). If the Playoff field is expanded, I wouldn't expect the Big 12 to expand either. They'd be guaranteed access if all P5 winners get in. The only way they'd add a new member is to replace any departing members. IF that happened, it's only going to be for football.