I've talked before in previous articles about the importance of art preservation and why preserving art benefits human culture as a whole. However, when discussing preservation the question of, "what is and isn't worth preserving" comes up often. We start separating art into tiers, such as "high art" and "low art". Preserving films such as "The Godfather" and "Citizen Kane" become priority over forgotten films like "Atlantis: The Lost Empire" or films perceived to be bad like "The Last Airbender" or "Fifty Shades of Grey". Despite our desire to preserve quality and weed out imperfection, I feel preserving all media, no matter the quality, is important for us as a culture overall.
First of all how does one any given work of art get broadly categorized as "high" or "low". The first signifier is the function of the art. Art that strives for a higher purpose and deeper meaning tends to get labeled as "high art". Things such as advertisements and pornography tend to get labeled as "low art" due to the shallow purpose of selling products or something as basic and primal as sex. However, by not preserving "low art" can people judging a culture based on its art make a truly complete judgement.
By only preserving "high art" you only preserve the best of humanity and discard ideas and concepts we deem undesirable. This can help societies progress in the fields of science, social interaction, and civil rights. However, by losing these "lesser" pieces of art we lose the context as to why they were bad and how to avoid their failings in the future. By losing these pieces of art we not only lose the history, but by not learning the lesson in that "disposable" piece of art we are run the risk of repeating that mistake.
A film like "Triumph of the Will" is a very nasty piece of Nazi propaganda and should never be taken to heart by anyone. However, I do feel that it should be preserved as a teaching tool. People should watch it and learn about the techniques used in propaganda so they can know where to spot it and how they can avoid falling for it. While Something as racist as "Birth of a Nation" is hard to stomach, people need to learn about racial stereotypes in media, the harmful history of "black face", and why we should avoid doing both in the future.
There's also the issue of how art changes with time and culture. For example, comic book superheroes are some of the biggest names in entertainment today bringing with it various forms of critical theories and mythological studies. However, in its day, comic book superheroes were seen as silly and disposable "kids stuff". Due to this, comics were not seen as worth preserving and many of the earliest comics that introduced some of today's most popular characters are either extremely rare or completely lost to time.
What was seen as frivolous and disposable then is viewed as important now and there is no way to know how time and cultural shift will change our view of any single piece of art. This is why preserving all forms of art is important, no matter how good or bad. When you can view it all you can get a clearer and more in-depth look at humanity. You can see it's greatest highs and it's loathsome lows, and hopefully learn to be better by examining and remembering both.