What you say is very practical but ignores a fundamental psychological trait of human behavior that is otherwise shaping the geopolitical landscape for centurie

What you say is very practical but ignores a fundamental psychological trait of human behavior that is otherwise shaping the geopolitical landscape for centuries all around the world. There are plenty of small countries in the world, that differ from neighbours only on relatively minor cultural details and whose main identity trait lies in having its own language. Acknowledging the existence of the desire of self-determination and sovereignty and the link between language and ethnic identity can explain a lot, both about the desire to persevere in talking less "useful" languages and also about the efforts to repress their usage by large states (which acquired territories that are not historically culturally homogeneous)