I attended a number of games at Memorial. Several of them were with my HS band as part of the annual "Band Day" event. Later on, I went to a few games at Memorial while I was a student at Augsburg.
the place had no amenities. bleacher seats, limited concessions, limited restroom facilities, etc.
So - as noted by other posters - it would have been fairly expensive to upgrade the place. Probably would have had to keep the exterior shell and gut the inside, then rebuild.
Considering the fight to fund the MetroDome, I can't imagine that the State Legislature would have provided much if any funding. So the U would have had to come up with.......$40-million or more.
Given the climate with the U administration at the time, that was not going to happen.
Speaking of Sid, at one point he was pushing an idea to build a stadium on the State Fair grounds to replace the grandstand, with the idea that the Gophers and Vikings could play there, and on game days, they could open some of the State Fair food vendor stands. that would have been unique.