Recognizing that people change tastes, and that this change in taste can result in works being lost, individuals and institutions since antiquity have selected works for preservation, so that they wouldn't be lost. The oldest known authoress, Enheduanna, had her works preserved in this manner. In our modern era, the Library of Congress has created the National Film Registry, which has films from 1891 to 1999. Sadly, none of the ST films is on that registry, but two Star Wars films, A New Hope
and The Empire Strikes Back
are on that list.