The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.
by leaving the states to adjust to the needs of the people, they gave the people the option of going elsewhere if they didn't like what a state was doing. state, if they engage in social experimentation, only harm those in the state if the experiment fails. if the feds do the same, they harm the whole country.
one of our very best freedoms, is the freedom to walk away from a state that does something we don't like and can't change. walking away from your country is a little more difficult.
jerrymac, the constitution is more about limiting the federal government, than anything else. even in the bill of rights, many things are directed only at the feds. congress shall make no law....etc. you have more options with a limited federal government and states that can have freedom to do what the people of the state want.