Why would you use an accent when it actively gets you associated with idiots / racists / conservatives?
There's a lot of people who have been hurt by Southern culture, so naturally they reject that accent. A lot of decent people reject the accent because they don't want people to assume they're one of those Southerners. There's also the aspect that you end up talking to people outside your region a lot more often than in the old days, so you learn to switch it off because people outside your region might not understand you well.
It makes me kind of sad to see so many people happy that the accent is going away. It's good to have diversity, and the thought of my "native" accent becoming extinct makes me sad. I don't want bad people to have a claim to an entire accent and culture, especially since the death of the accent won't do anything about the bad takes. There's a lot that good about southern culture - taking things slow, being laid-back in a world that wants you to run around like a chicken with your head cut off, and forming tight communities with the people around you. I just wish there was a way to reclaim that without feeling afraid that people would assume I support the bad parts, too.