At one point in time I wasn't a fan of averting the model's face, or, leaving it out of the image all together, the issue with the face however is when it's included, the photograph becomes a nude portrait because the face personalizes the picture.
Window Light Lines
By averting or avoiding the face, the photograph becomes more of a study in body, light and lines.
Shades Of Grey
In years past, photographers would more often be shooting nudes with acquaintances, friends or lovers, things were not like they are today now that we have multiple modeling sites on the Internet where photographers can virtually shop for a model.
Also, being friends or acquaintances and not models, many times the photographer was required to keep the identity of the model confidential.
"Edward Weston understood thoughts and concepts which dwell on simple
mystical levels. His work--direct and honest as it is--leaped from a
deep intuition and belief in the forces beyond the apparent and factual.
He accepted these forces as completely real and part of the total world
of man and nature, only a small portion of which most of us experience
directly. . . . And it was Weston who accomplished more than anyone,
with the possible exception of Alfred Stieglitz, to elevate photography
to the status of fine-art expression."--Ansel Adams