If plays are considered literature why aren't movies considered literature as well? In the same way that plays are meant to be seen, but are adapted from paper, movies are meant to be seen but are adapted from paper as well, so what makes them so different that they shouldn't be considered literature while plays are? Is it some sort of difference between how the script for a play and the script for a movie are done? No, they're basically the same, and the differences shouldn't be enough to suggest that movies can never be well written. If movies can be well written, which is the case, then it's wrong to cast them aside as inferior to poetry, novels, plays, essays and other accepted forms of literature. There may be a few differences between screenplays and other forms of writing, but that doesn't mean that the written-down form of movies, at least some, aren't good enough to be considered literature.
It's incredibly presumptuous and arrogant to say that every single movie is badly written and doesn't deserve to be considered worthwhile as literature. Many movies may have incredible directing, acting, cinematography, special effects, music, sound editing and everything else that makes a movie worthwhile, and obviously these things don't apply to books, or the contents of books, but movies and creative fiction have enough in common for movies to be seen as a form of creative fiction. The characters, the plotline, the theme, the setting, the symbolism, the irony, the complex hidden meanings, and everything that has been put together to create artistic unity, the stuff that makes fiction powerful and memorable, the stuff that brings us insights about life in general, these things exist in movies. If a movie achieves all these things incredibly well then why shouldn't it be considered literature? People think no movies have all these things in them, but that is not the case.
A person's knowledge of movies is often restricted to what Hollywood suggests, and Hollywood doesn't necessarily produce or promote literary movies, so it's as if such movies don't exist, but that's not true. They're often pushed aside by the hugely-hyped movies with little literary value, or their literary value isn't noticed, but in and out of Hollywood, they exist. Charles Kaufman, the Coen Brothers, Wes Anderson, Stanley Kubrik, Robert Altman, Christopher Guest and Alfred Hitchcock all make very intelligent, very thought-provoking films with strong themes. In fact, I'll list out such movies:
Adaptation, Eternal sunshine of the spotless mind, Being John Malkovich, among others
The Coen Brothers:
Barton Fink (my brother spent a long time studying this film and came to the conclusion that it was about the death of creative fiction), The Man who wasn't there, A Serious Man, and many many more
The Royal Tenenbaums, Rushmore, and others
The fact is that movies by directors such as Charles Kaufman and the Coen brothers are incredibly well done and overflow with strong characters, symbolism and other techniques. Watch these films and you will see that they have immense literary value, are completely original and are incredibly brilliant. The only thing that should stop us from considering them as literature is the fact that we never see their written-down copies (but we get a glimpse of them at the Oscars when they're announcing the Academy Award for Best Writing (Original Screenplay). It is, however, a fact that such written down copies exist, because without them the movies wouldn't have been produced. The literary values that we see on screen are really adaptations of the literary values on the original scripts. Without the written down copies, the literary values wouldn't exist, and in fact no part of the movie would exist for that matter. So the writers who originally created the stories of the movies, the screenplays (which are hardly different from the plays we love to consider as literature), are authors, and their works are written-down pieces of creative fiction that represent the language, culture and period of the author (which is the definition of literature).
Although the movies themselves aren't literature, their screenplays are, and we shouldn't degrade and ignore them just because they're presenting themselves in a different way. Obviously, most screenplays wouldn't be rich enough for you or me to consider as literature, but some are and it's not fair to them, or their authors, to automatically shaft them as inferior.