You're right in that, identity is not enough. But to a Sorabian, his community is a part of his life. It would be inappropriate to tell him something like that he should not waste his time with that useless language but speak German only (or English only). Ziko van Dijk
That's the crux of the question, though---is supporting linguistic identity, even in cases where it doesn't serve to communicate information to a wider range of people, a goal of the Wikimedia foundation? Some interpretations of the mission statement have said no.
-Mark