Westphalia was created to replace a set of hostile principalties and microscopic fiefdoms by an unique german state applying the principles of the french empire : unified territory, modern administration, separation from church, equal citizenship.
In other german states, legitmacy meant that such reforms, although also present (e.g.: abolition of serfdom in Bavaria 1804), should be implemented with agreement of existing political and economical actors.
So newly created german states, if successfull, could provide an incentive for reforms in other states, by showing the prosperity and stability induced by a "modern" state for its citizens. Also, it created a natural ally in the heart of Germany.
OT, controversial: like trying to replace a dictatorship by a democracy in a Middle Eastern state, as a counterpiece to radical muslim "allies" states.
Problem was, it turn to be unsuccessfull : frontiers were constantly moving according to french interests, not local ones. Existing infrastructures were not adapted to a centralised state, and the necessary ressources to settle this were absorbed by France through pensions and aggressive customs policy, again against local interests.
Having a young, stranger monarch without the will or possibility to oppose his brother, deprived the locals of any negotiations latitude.