Physical media is more than just its' content, There is a history to it. The faded parchment of an old book can reveal more about the time it was made than one might realize. Maybe the book went through the Kristallnacht and has a scorched look to it that symbolizes the torching of homes. Or maybe the book contains a lot of rat droppings because it was made during the Great Plague. Stuff like this is the reason physical media should be preserved; for history's sake.
Not to mention, Certain pieces of media would not be the same without a physical counterpart. Take, For example, A painting. The feeling of a painting can be very different online. This is because lighting and perspective are very important to the experience. If you post pictures of the painting at the angle it would be observed in real life, Some parts of it will inevitably look blurry unless it was intended to be looked at at a front, Face-level point of view.
Another important purpose of physical media is as a backup for online copies. Sometimes, Mistakes are made, And online copies of media disappear. If we have the physical media, However, Those mistakes would not be as disastrous as they could be.