Re: "Just turn the question over to the states"
To be sure, there is no guarantee that states or localities will make all the right decisions, but decentralizing the power isolates the bad decisions. When everything is national, one screwup affects the whole country.
The key to good government is not to have too much power in any one place. Any argument that can be applied to economic monopolies can be applied to government ones, and for the same reasons.