1. It was formed, not by the governments of the component states, as the federal government for which it was substituted was formed. Nor was it formed by a majority of the people of the United States, as a single community, in the manner of a consolidated government.That's why it had to be state conventions. They needed to derive from the same authority that made the state constitutions, so that they could legitimately supercede and nullify state constitutions at will. I'll give Madison credit for being fair. His project was a stinker, but he did it on the up and up.It was formed by the states, that is, by the people in each of the states, acting in their highest sovereign capacity; and formed consequently by the same authority which formed the state constitutions.
As for why they kept states around at all, the main reason was political expedience. Again, from Madison:
Conceiving that an individual independence of the States is utterly irreconcileable with their aggregate sovereignty, and that a consolidation of the whole into one simple republic would be as inexpedient as it is unattainable, I have sought for middle ground, which may at once support a due supremacy of the national authority, and not exclude the local authorities wherever they can be subordinately useful.--letter to G Washington
As for the Hamilton groupie nonsense, it just shows what a drooling moron you are. I have not expressed any special admiration towards Hamilton. I see him as a villian. But facts are what they are. Unlike you, I can recognize facts without throwing little baby tantrums.
Ad hominems = seeya, scum.