There is no performance without performers. Audiences expect artists to be at their best, and rightly so. Artists, meanwhile, also justifiably expect to work in a building which enables them to perform at their best.
They want a pleasant changing room, not too far from the stage, a welcoming greenroom where they can have something to eat, and decent washing facilities so their performance does not end with a cold shower.
Nothing outrageous or expensive, but worthy of attention.