Indeed, once the principle of States rights were overthrown by force, it has been a long slide dowm.
It is always the goal of anyone interested in power & wealth to pursue centralization. The principle of states' rights was a con from the very beginning. Any good salesman knows to sell the sizzle, not the steak.
The southern states fell for the ruse, and learned the hard way about their mistake. The constitution was a key component in providing the crucial nexus in "justifying" the war.
However, if there hadn't been a constitution, the northern states would have simply attacked & defeated the southern coalition under pretenses no differently than with Mexico.
Might makes right, and people who constantly complain & whine about 'principles' seem to ignore that territorial acquisition is the age-old method to gain further wealth & power.