What's changed?
Democrats were always seen by Republicans as evil incarnate, out to ruin the country. But then Clinton came along and the 90's were- a pretty decent decade. I think people remembered that when they voted for Obama. So why have the Democrats jumped in the deep end with their pockets full of rocks?
It's not the first time they've been in power.
But there does seem to be a correlation between the times of Democratic free reign and scocial change
(Funny, the only social change I remember during the Carter years was the forced conversion to the Metringlish system which we still suffer today.)