Today, the federal government with its billions in income tax revenues is the center of power and most feared source of oppression in the US. In the days before federal income taxes, things looked different to some Americans. Those in the back country, habitually outvoted by clever lowlanders often saw less to fear in distant Washington than in state political elites. Whatever the sentiment against federal revenue agents, state government and its decisions affected the lives of highlanders more and produced greater friction and animosity.
At the other end of the social scale, many wealthy citizens, including more than a few big Delta planters, feared the levelling Jacksonian passions of local Democrats and trusted the federal government and the Whigs to keep the ship of state on an even keel. And of course, African Americans in the South on the whole had more to fear from local than federal authorities (in some Northern states, though, things looked different, as US Marshalls hunted runaways and state governments passed "personal liberty laws" to prevent extradition).
One way confusion sets in is the Celtic-Cavalier thesis. On the whole, it's probably true that those in the hill country were more Irish or Scots-Irish or North English than those in the flatlands. But it wasn't the case that everyone whose ancestry was "Celtic" was poor and every "Cavalier" rich. Rich lowland families like the Butlers or Bullochs might be related to the Irish or Scots nobility. A poor, but enterprising Irishman might find his fortune in Georgia or the Mississippi Delta. A great Tidewater family like the Washingtons, Randolphs or Byrds would apparently have poor cousins in the West Virginia highlands. In the Piedmont, where Madison and Jefferson lived, and in the lands beyond the Appalachians Celt, Cavalier, and even Yankee might intermarry. And the largest settlement of Scots was in the lowlands in the Cape Fear area. There definitely were deep divisions in the White South, but the Celtic-Cavalier theory can blur as much as it clarifies.
Many of those whose ancestors would have been very critical or hostile of the Confederacy in the 1860s, now assume it spoke for them and fought their fight. It's an indication of how historical understandings change and symbols take on different meanings, but it shouldn't be allowed to govern our understanding of the past. Present-day political divisions get projected back on the past. People want to believe that all the libertarians were on one side and all the statists on the other. In fact, things were much messier, and confused by regional interests and the issue of slavery. Many who think about the Civil War today tend to get their wires crossed, taking the near anarchic freedom-loving spirit of the back country or Britain's Celtic fringes for the inspiration behind the Old South or the Confederacy, when in fact the positive state-building impulses of the lowlanders played a crucial role in the history of the 19th century South.
The United States grew out of the interaction of a variety of different groups. It's certainly possible to wish that history had unfolded differently, but it's doubtful that one group alone -- whether libertarian backcountry pioneers, public-spirited Virginians, learned Yankees, pragmatic New Yorkers, or temperate Philadelphians -- could have done a better job by themselves without the moderating or inspiring influence of the others. Left to themselves, the various groups that made the country would probably have done a worse job than the nation to which they all contributed did.
While there were indeed opponents of secession in the so-called "backwoods" of the south, you severely overstate the unionist sympathies among southerners at the time. Every state that held a secession referendum saw it pass in a landslide. Even the allegedly unionist hotbed of West Virginia voted in a majority for secession. The unionists there were for all practical purposes a rump government of sore losers - almost half of the counties they claimed as their own had voted for secession or had pro-secession delegates in Richmond. The only other significant unionist hotbed in the undisputed CSA states was appalachian Tennessee. Middle Tennessee and western Tennessee were solidly secessionist though and offset the eastern minority in the referendum.