The "logic" is that the states existed before the federal government. They gave up power in certain specific areas (national defense, customs, interstate commerce, and in the minds of the Founders, that was about IT) in order to have a functional national goverment capable of defending the union against the likes of Britain and France. The states did NOT give up the police power. Otherwise, they would have become mere provinces. It was deemed to be within the power of the people of each state to determine just how intrusive the police power of their particular state would be.