BYU has a unique mission, a unique student body, and a unique philosophy. It also has a far better perception as a program than Utah with the National Championship, the great QB's, Outlands, Doak Walker Award.
Notre Dame's brand suffered a bit during their long period of mediocrity...but they were still Notre Dame. BYU is not Notre Dame...but they have a unique brand and in the Bronco era have made enough noise to at least perpetuate the brand. People in Texas know BYU. They don't know Utah. They simply don't. I have lived all over the US. BYU has a brand. Utah...it's lost among directional schools.
BYU's sole selling point for years has been the anti-BYU. The dark side to BYU's bright side. They gave that up for a mess of pottage. They will be an afterthought. Maybe some occasional splashes, but they will be an afterthough.