If art has value, then its form has value as well since art devoid of form is just communication which is no longer art.

If the form of art has value, then the original form of that art has at least as much value since it reflects the original intention of the artist which inherently has value by being part of the historical record.

If the original form of art has value, then there's value in preserving it for future generations to appreciate.

If there's value in preserving the original form of art, then there's value in distributing it widely since history has shown time and time again that copyright holders alone are not enough...

    1. https://en.wikipedia.org/wiki/1937_Fox_vault_fire

    2. https://en.wikipedia.org/wiki/1965_MGM_vault_fire

    3. https://en.wikipedia.org/wiki/2008_Universal_Studios_fire

    4. https://www.bbc.co.uk/archive/bbc-archives--wiped-missing-and-lost/z4nkvk7

    5. https://faroutmagazine.co.uk/the-steely-dan-songs-on-aja-that-cant-be-remixed/

Why would it be not OK?

For the same reason removing party figures from pictures with Stalin was Not OK. Historical preservation is important, if we care about truth.