You're assuming that just because states have that power (assuming it's not prohibited by their own constitutions), they'll therefore exercise it at every opportunity. It doesn't necessarily work that way. There are political consequences when politicians try to do things like that. But with the federal government, it's both harder for citizens to exert control over government, and more dangerous when the federal government goes beyond its bounds, because its control is nationwide.
Of course the majority will exercise their power at every opportunity. Jim Crowe was majority rule.
People seem to forget that each state has a constitution, which that State must obey.