lesser sports. The possibility of added money and exposure on Sundays is one of the few things that athletic departments can offer to give the non-revenue sports some added prestige. If BYU competes as well as we think they would, there would always be the desire to put one of our games/matches/tournaments on a Sunday.
Last I checked, the Big12 had 8 sports that had championships that were either on or included Sunday play. The ADs would have to fight their coaches and administrators in those sports to eliminate Sunday play, not to mention the bind on conference administrators.