A lot of the newer stadiums being built these days are taking pages from European soccer stadiums with a partial roof ringing the seats (see Buffalo's plans
here, and the Chiefs are considering something similar). This apparently does an excellent job of loudening the crowd. It's why Allianz field seems pretty loud despite a smallish seating capacity.
Not sure the Gophers stadium is structurally capable of adding something like that and it's likely pretty costly, too. It also might eliminate being able to expand vertically.
But. it'd look cool...