Good post, and good point.
What you are seeing in the constant revisitation of American Civil War subjects is the broad joining of a debate over the character of the American governmental experiment, and the attempt by academic Marxists to hijack the subject to their own purposes, in much the same way that Dalton Trumbo and the other Hollywood communists tried to hijack H'wood's message machinery to put out Marxist-Leninist themes. Good examples are most of the films Burt Lancaster appeared in, in which, if he were playing the Marxist vanguardist Good Guy, the townspeople (the Bourgeoisie) were always vilified as low-ethics, low-courage, low-virtue, and generally contemptible.
In the current conversation series, the so-called Neo-Confederates (and the other side mostly calls them that) are arguing a series of constitutionalist and sectionalist positions, against Marxist themes of "people's revolution/liberation" propagated from the top by Lincoln and the Republicans (vanguardism, again).
Where the Marxists want to go is, to validate Government as the Sovereign, and the elite Vanguard as the proprietors of the Government. They have something to work with there, because something very similar is what Lincoln had to do, in order to justify getting rid of slavery by armed force and constitutional novelties. To trump the secessionists' constitutionalist arguments, or at least to meet and dispute them for political purposes, Lincoln had to posit a competing theory of Union that redefined the Union, the People, and Sovereignty. That is the Marxists' beginning material. As someone noted in another thread, it may be very significant that Marx himself approved of Lincoln's political theory and his war, a congruence that the Marxist apologists, of course, are a little shy about advertising; but instead, they pick up Lincoln's arguments and run with them.
To complete the hat trick, they identify their own politics as neo-Lincolnian, or standing in a tradition going back to Lincoln, and use his public cult as the figurehead of their own intellectual and political assault on the sovereignty and freedom of the American People.
That's what the food-fight is all about.