I think they were trying to draw a parallel.
You have mythological creatures, but it is also the Old South. All the cherubs look like blond baby Elvises(sp?) or something, the lady centaurs are like southern belles, etc.
Of course I could be reading too much into it. Still, people today go out of their way to be offended by things.
Btw, I remember sitting through Fantasia in a theater when I was a kid... and it was dull then too. It has never been, and never will be a film for kids.