Studying a bit of
history and
world cultures is enlightening. Eroticism seems to be all about teasing, about exploring the edge of your culture's boundries of naughtiness
In Victorian times, catching a hint of a women's ankle was sexy. The same is true now, in cultures that require women to wear dresses that cover entirely.
In the 1800's in the US and Canada, women were socially required to pin up their hair once they were considered adult. In those times, hair flying free was eroticized.
And today, I can name a body part that is always uncovered and that clothing for it is eroticized: your face. Masks are very sexy.