"The states didn't secede over slavery, it was because they hated federalism" is the new PC revision. And the sudden emphasis on confederate blacks that you noted has jumped to the forefront suddenly simply is another tool to use in a deliberate attempt to prove that slavery wasn't THE issue, at all, that slavery was just some coincidence or side issue, that the real cause of contention was something else.
IMHO this is Confederate political correctness. It makes those of us who advocate the Southern cause look ridiculous to other people, especially anyone who has read much written at that time (1850s and 60s).