Answer:
First, this gets to the matter of "why federalize?" We federalized to meet an external threat. There was England, to be sure, but the colonists were also well-traveled and could make their own predictions about Europe, and we see that, no matter what they might have predicted, France did indeed become a grave threat. So one reason (and this implies there are others) is to meet an external threat. What other reasons might there be? I don't know. But I would immediately jump to the thought of an internal threat. So you might think about that. The southern colonies never liked the constitution, and they became a threat soon afterward. One source to look at is Novus Ordo Seclorum: Intellectual Origins of the Constitution, by McDonald. But let me get back on point here. Federalism is not the only way to meet the needs of a nation. There are other options, such as unitary state. But we had a system of entrenched states, and we had inherited a common-law tradition in which the sovereignty of local governments was hallowed by tradition. And we had just fought a war of separation that revealed the weaknesses of a confederacy; it's not unified, and a confederacy doesn't cede any power to the center, so there is no strong national defense with a unified command, which is vital to warmaking. When a group of local governments, or baronies or cantons or states or whatever, confederates, they are limiting power to the center, but all that does is shift power over people to local control. The nation's first government, the First Continental Congress, was not able to hold the nation together under the strain of these wars between France and England. Witness George Washington's difficulties holding the army together as he was outmaneuvered and chased all around Baltimore and New York by the British commander, Howe (who was under Cornwallis).
So there were 2 sides to the debate: the Federalists and the Anti-Feds. The Feds were actually anti-democratic. They wanted to limit the impacts of faction. This is a huge debate. The Feds are represented by "Publius," the collective name for John Jay, Madison, and Hamilton. They won the Constitutional debate.
Jefferson was not a framer of the Constitution; he was in France when it was signed, and he was an Anti-Fed, and this is the party that lost the debates. His contribution to American political thought is the thought of a living document. He wrote the Declaration, which is based on Enlightenment liberalism ("classical liberalism") and he felt that people were best governed by a "natural aristocracy" of enlightened freehold farmers. This does not preclude owning slaves, by the way. The liberal argument (which is really the only argument) for justifying slavery is that you can"t interfere with the natural right of a man to own a slave. (!) This is the argument later on during the Civil War, in Calhoun's "Southern Defense."
The Federalists were the "Radical Republicans." The Anti-Feds were the "Jeffersonian Democrats" or "Democratic Republicans."
Later, Jacksonian democracy took hold. This was the thought that drove Manifest Destiny and encouraged the pioneering spirit. The Jacksonian Democrats relied heavily on government assistance since they were pushing westward. So there is this ideally-democratic thought of self-sufficiency: instead of being "self-sufficient" in the Jeffersonian sense, the pioneers prized hard work and the ability to fix whatever needed fixing. It gave meat to the phrase "American ingenuity." It also fueled women's rights and suffrage later, because pioneer women were expected to work just as hard as the men. They showed that they were not just Eastern Belles who relied on men for their station in a leisure class.
But at the same time, the Jacksonian Democrats, for all the talk of self-sufficiency, relied on the government for assistance. They were pushing westward before, during, and after the Civil War, which is when the Indian Wars were taking off, with their presence pressuring the Indians. So pioneers settled around forts for protection, and they required assistance in linking up transportation networks on land and in the riverine systems.
Conservative democrats favored the South, which was trying to keep the East and West from linking up. The linkage would mean the death of the Southern Master class, which was dependent on slavery for its economy. Calhoun pushed to have the country form up into 4 "economic zones," each region having veto power over the other. This was just an attempt to stall the inevitable economic linkage of the East and West as the nation grew. In 1857, Dred Scott split the Democratic Party along abolitionist lines. Chief Justice Taney was a Democrat, and the dissents came from the 2 Republican justices. So it rent the Democratic Party in two, with Dixiecrats on one side and the "progressives" on the other. Eventually, the conservatives in the Democratic Party defected to the GOP.