I love that this movie is rated so terribly because it makes the point.
The point:
Making white people uncomfortable is, in some cases a death sentence in America for people of color. The joke being, in the case of this movie, that the entirety of the movie was to make white people uncomfortable. It's a comedy for crying out loud. The fact that it made white people uncomfortable to the point of bombing this movie, much like having a black Ariel, makes it even funnier. This movie is a classic that hopefully one day we will look back on and laugh at together, regardless of race. Hopefully, we will laugh at the chasm of understanding between the races
The reason why this movie was not good per se for everyone watching is because it was deeply cultural. If you are not apart of the culture, then it wasn't for you, and you have no frame of reference to understand or even laugh at.
This was a huge artist risk for the writers, actors, and producers and it for those who it was written for we recognize it as such.