In support of the ideal of citizens as informed, rational and responsible people (mündige Bürger).

This is a foundational assumption of post-Hobbesian democracy, which asserts that power originates from the people and is delegated to the government (contrast to other political philosophies such as divine right of rule etc).

so the consequence of 'dumbing down citizens' is a destruction of the legitimacy of the government. Just as if the king rules by divine right, he would be silly to promote atheism.