Not all plays are better than all movies, and not all movies are better than all plays. One of the best things about many plays is that they are the inspiration of a single author, like Shakespeare or Tennessee Williams or David Mamet or George Bernard Shaw. One of the worst things about many movies is that they are put together by a committee. Good plays are often much more sincere than movies because the actors present them in a single performance which is uninterrupted except for an intermission. Movies, on the other hand, are put together piecemeal. The actors often do not even understand the scene they are involved in, because the scenes are not always shot in the order in which they appear in the original script or in the shooting script. The scenes in the shooting script are given numbers, and several scenes may be shot which do not have consecutive numbers, simply because they all occur in the same set. The film editor has a great deal of importance in determining how the finished film will look. But so do the director and the chief photographer. And the producer is always interfering because he is concerned about the budget.
Many movies are created just to make money or to give a star something to do. A moviegoer gets to recognize the various stereotyped plots, such as the love-comedy, the gangster flick, the revenge story, and so on. Nowadays there are many movies that rely on special effects intended to wow the viewer but totally lacking in sincerity. If an intelligent person is looking for dramatic entertainment with sincerity of emotional content, originality, intellectual value, and thematic significance, he or she may be motivated to see a good play performed by live actors who believe in what they are doing.
There are many young men and women who try to pursue a theatrical profession whose early years will of necessity be spent in working in live theater, either as actors or writers. These people deserve to be supported and encouraged because they represent the future of drama. Even attending a play produced in a little theater with fewer than a hundred seats can be a pleasant and stimulating experience for the viewer. There is a feeling of "sharing" with the audience and "sharing" with the performers. Going to a movie can be a disappointing experience because it is "canned entertainment" put together to make money and sell popcorn. The development of megaplexes has only made the moviegoing experience more mechanized and unrewarding. Many of the best movies, such as A Streetcar Named Desire and Cat on a Hot Tin Roof were originally stage plays.
William Goldman, who wrote Butch Cassidy and the Sundance Kid among a number of other excellent films, wrote an enlightening book about Hollywood moviemaking titled Adventures in the Screen Trade. Please refer to the link below.