Not a "must", but definitely "preferred":
1. Understanding that stadium design cannot accurately reflect real-life examples, a much better default stadium in the match engine. It is depressingly disappointing to watch games in top professional leagues and see:-
Wide areas of unused concrete at the corners
2 metre brick walls at the back of these areas
Ambulances parked on the pitch side
Burger vans on the pitch side
50,000 all-seater stadiums and 2 picnic tables with seating for 8 people.
Just fill in the corners with seats and forget about all of the above.
2. Realistic regen faces- some of the current ones are very poor, especially when half your youth intake has beards.