Well mostly by the club and Emery because they have to decide if he's a first-teamer or not. Rotation or back-up on 120k a week is not really something we can afford to do.
From a fan's perspective, wages set a baseline of performance expectations; the higher they are, the more you expect from the player because of the financial resources committed.
It doesn't make any sense to me to not be bothered about that sort of thing when the financial wellbeing of the club is incredibly important and as we saw under the Lerner/MON era, we have to be careful.