What is totally inexplicable is why anyone with any human feeling would have any regret that a system as odious as that exemplified by the antebellum South was eliminated from a free nation's existence.
Well I am truly sorry but I don't see where ANYONE who is defending the Confederate battle flag has made any sort of argument FOR slavery or any argument that we shouldn't have eliminated slavery as a nation.
The history is this... The North fought the South in the Civil War over MONEY! Not slavery, not human rights, not over racism, not the Constitution! Like almost EVERY war, it was over MONEY! Lincoln was asked, "why not let the Southern states go in peace?" His reply was, "who is going to pay for government?" He knew it would be economically disastrous for the US if the South were allowed to secede and that's his reason for fighting the war.
BUT... Like almost every war we've ever been involved in, the "reasoning" has to be couched in some moral "right" that we are fighting for in complete denial of the fact that we are actually fighting over money and financial interests. In the early stages of the Civil War, the Union was getting her ass kicked pretty good by the Rebels, and Lincoln HAD to come up with something to unite the public behind the war, or it was going to turn really ugly for him in a hurry. So he issues the Emancipation Proclamation and makes it about slavery.
The South was actually in the process of eliminating slavery. Slave markets had been eliminated. You couldn't go and buy slaves anywhere in the South. Technology was going to eventually replace slave labor and Southerners knew this. Still, they had invested a billion dollars in slaves as property because the US Congress and SCOTUS told them this was acceptable and legal for the previous 85 years.