The second one is centrifugal. It appears as an answer to unification process. The Europeans living in a huge unified state called EU want to underline their local peculiarity. They begin to wear their national costumes (even in only one detail, like embroidered shirts or chemises), to renew relics of the past, to use local dialects, the dialects are included in school programs. I think that a man wants to express his individuality, and an availability of in-hose enables him to do it in the simplest way, that is by speaking in his local dialect, if he doesn’t want to be bothered or if he is not mental capable to use a literaly language.
I suppose that both tendencies are equivalent, because you know, states in Europe arise in XXI century too, near borders of EU.