Copyright is theft. Theft by giant corporations of 95 years of culture (minus a modest number of works licensed under cc0) that belongs to the People. Copyright is the worst sort of time machine. What does a world look like where early Schönberg is now hot off the presses? That is now our new music! Worse yet, there is a late Liszt work that I cannot find in an uncopyrighted publication. Worse yet, there are Christian Bach symphonies that I want but publishers stole 270-year-old music from us.
Another work that should be public domain but that I can't find in a cc0-licensed version: Alice Mary Smith's Symphony in C minor. I believe robynsveil at musescore was working on digitizing this, but it does not seem to be complete yet let alone cc0-licensed.