smiling for no reason is insincere and indicates foolishness. There is even a saying in Korea that states, “He who smiles a lot is not a real man.”
In many Asian cultures, smiling is seen as a sign of embarrassment or as a symbol of frivolity. For any serious matter, a smile would not be deemed appropriate. One Korean saying, “He who smiles a lot is not a real man,” is a good example of how many in Asian cultures both respect smiling enough to reserve it only for true happiness and deplore its overuse as unnecessary and flippant.