This is strange conflicted space for me. Were this the case, Disney would have had to produce nothing but original work, which would probably benefit us today but would leave us without the eventual cultural heritage that they produced (if it can ever be pulled from their claws). I'm coming more and more to the conclusion that public domain is very much like other idealogical freedoms I was raised to believe in, which is to say beautiful conceptually but possibly messy and requiring potentially painful sacrifices on the part of individuals if consistency with the ideal is the goal.
Thing is, Disney has profited immensely from public domain, and then they have done everything in their power to restrict public domain as much as possible.
Works have to be released into the public domain, or there will be nothing but licensed regurgitation of the same things.
Indeed Disney is a great example. It is because of them and their greediness that copyright protection was extended so past reasonable duration in US and other countries...