Retarded answer. I'm not saying that it's a necessary pattern, nor that they are or should be the strongest regions of their countries. If anything, the fact that they're not the strongest regions of their countries actually helps explain why they might be left out> no matter how strongly nationalistic they might feel about certain identity, they're still peripheral to such national identity, and thus can be sacrificed or excluded.
Still, it's a rather weird phenomenon. Germs tend to see prussian unification as the birth of modern germany, yet this same unification is what brought about the end of prussia and pomerania. They lost a big chunk of what was traditional german territory.