The argument that the Nations League is "unimportant" makes no sense. If it's so unimportant, then teams taking part in it can afford to change things up, by using different players, testing new formations, etc in a competitive environment, instead of being limited to friendlies, Euro/WC qualifiers and the main competitions themselves.
Each national team has the choice to either take it seriously, and play their best eleven, or they can simply use different players. The format of this tournament is actually important for smaller teams, that end up playing with teams of their level, instead of being battered 5-0 or more by the "big teams" in the Qf games.
