Not everyone can be a college athlete. The band, dance teams, etc. provide extracurricular activities for kids who just aren’t built to play football/basketball.
Bands, dance teams, cheerleader, student section, even concessions, give the other 99% an opportunity to be a part of the event.
I agree with what some have said above. This isn’t the NFL. This is college football. And the band is part of the college football American game day experience/tradition/culture. And I imagen at BYU especially, a goal is to allow all an opportunity to share their talents.
Having said all that, I’m not there to watch the band. I’m a football fan and I’m there to watch the game. But I am ok with the band serving a purpose and giving those kids an opportunity to be part of the event.