I think another reason for their failure is the same reason the bottom has fallen out of the antiques market, because of changes in the culture, people don't have the respect for the past like they used to. Toppling of old statues, renaming of all sorts of things to have no connection to the past or history, the rewriting of history in popular shows, etc, are all sort of extreme reactions against the past and tradition and it's reflected in a fall in demand for older culture.