The fact that slavery was ended, is the ONLY good thing about the Confederacy losing. The fact that the government by the states also ended wasn't good. The fact that Lincoln started a precedence of ruling by Executive Order isn't good. The fact that the invasion and destruction of the South's economy for 20 years or more isn't good either.
Then there is the issue of the South's traditional way of life and culture, and how that was almost destroyed.....
I've never quite understood what it was about the life and culture that made it so weak it couldn't self sustain? How exactly did the north destroy a culture? Frankly, I think much of what passes for this nostalgic view of the south is pure myth.