The old Marriott Center rows and LES rows were designed for short people. I think you would find it nearly impossible to get in & out of rows if you were to add those back rests to LES benches.
If BYU wants to increase the revenue it needs to continue improving the in-stadium experience. An example would be to reconfigure more seating similar to what was done in the Marriott Center, perhaps particularly below concourse. Another example would be to win more games 🙂