You make a fair point. But it’s one that must be applied VERY sparingly. After all, their are ethnic Germans in Poland who wish to be free from Polish control.
And their are ethnic Hungarians in Romania who wish to be free from Romanian control. (I am related to some of those Hungarians, by the way. They are VERY resentful of the position the Treaty of Trianon put them in.)
Etc.
Should we just accept endless wars of liberation?
Probably. I've seen videos on youtube of the time lapse of Europe for the past 1,000 years. I've got no reason to believe the map as it existed in January of this year is the map that must exist going forward through the end of time.