The problem is in how the beast is civilized

Nietzsche didn't want to “tame” man with morality, but rejecting morality is a form of taming man, and this is Nietzsche's form of “improvement” which he otherwise condemns in priests. Nietzsche's preferred “immorality” mostly applies to individuals, especial genius individuals, it overlooks natural group selection, which is the prime unit of selection, and group selection requires morality and the natural “taming” of man.

The problem is in how the beast is civilized. Rousseau and Thomas Paine saw primitive and natural man as a wild, free, and innocent, individual, as if group morality were not just as primitive and naturally evolved over the tens of thousands of years when man became man. Edmund Burke had a better grasp of the naturalness of group behavior (before sociobiology) and the civilization that naturally grows up around it.

Our instincts, passions and reason can be enlisted in service to our higher evolution, and higher evolution does not merely “tame” us, it makes us healthier as we move toward the zenith of truth, goodness and beauty. As with artists, geniuses in various fields can be as free as they need to be during the creation of their work, (they probably actually need to be free during the creation process), but then it is most natural for their work to be judged by the cultural needs of the group or by group morality, which is more important than individual morality.

 
What happened when the Nietzschean geniuses of modern art (or philosophy for that matter) had no group or social concerns? By any sane standards we received mostly garbage. For example, with psychometrics today we can almost easily distinguish the social geniuses from the anti-social criminal geniuses, and our grants and work awards to individuals would follow after this lead---but always leaving room for those few who fall between the psychometric cracks.