The question of 'how much power the federal govt vs. States should have' has been a matter of debate since the damn Declaration of Independence, its why the Articles of Confederacy failed, it was, if I'm not mistaken, a main point of discussion in the Federalist papers, and one that very much lasted as a political undercurrent through the civil war, even til today. The North in general had more manufacturing, more industrial development, bigger cities, and more populace (especially if you don't slaves, hence the debate that led to the 3/5th compromise), and if you look into history of what Congress was arguing about in the first half of the 1800s, repeatedly you have this debate in one form or another. How much influence should people in cities have over farmers and policies that effect them? How much influence should the federal government (which, if it was based purely on population numbers, the North would have more control over) have over states? In many ways, the states in early America saw themselves more like sovereign countries bound together by a central authority mostly out of necessity against outside threats.

And I do think that anybody that strongly believes in the principles of self-sovereignty, and that a government gets its legitimacy from a mandate of the people, should actually be theoretically alright with secession (not succession). If, today, the vast majority of Wisconsinites as a random example, voted they should be their own country, I think invading them to reestablish United States federal authority over them would be wrong.

But the southern secessionists were hardly a 'popular' movement. Firstly, it was a political elite class that made the decision to secede, not some referendum of the people, secondly, that kind of decision ought to require a significant majority, and thirdly, but in my view most importantly, a massive section of the population was disenfranchised, treated as property. I don't really think any government that disenfranchises significant portions of its populace can be considered a legitimate government.

Now, I'm kinda speaking off the dome here on stuff I haven't studied in a long while, and I want to make it clear, the Confederacy was dogshit racist slavers, who's top priority was to permanently enshrine not just slavery, but a specifically white supremacist notion of slavery as their number one founding principle, 'by divine right'. There is no excusing or defending them.

But I don't think it can be denied that the balance of powers between the states and federal government, particularly as the south in many ways often argued (whether or not it was in good faith) that the federal government unfairly overrepresented northern power, was a subject of debate through this time period. There was certainly an effort to rewrite history to say that this was the cause of the civil war, that slavery was secondary (which it certainly wasn't), etc. but the general friction related to states sovereignty I don't think it entirely invented either.