I believe morale is cosmetic too, but I make sure my players are on Superb, no matter what game it is, just to be safe, better to be safe than sorry in my opinion.
Morale is not cosmetic , it have a effect but we don't know how much in % . I s primary an indicator of the state of the player , form there you can understand he is not performing or he is performing ( also from ratings, mostly , you can understand this )