In some ways, the plentitude of visuals can detract from the simplicity and power of the words of a drama. Still, it largely appears that there is an inverse relationship between a drama's visual elements and its main focus - words. Watching a play on stage provides a lot of visual elements, while watching a play in a movie provides even more visual elements.
Reading a play in a book, for instance, offers no visual elements. All three of these media present a unique experience for the reader or viewer. The three principle ways that one can experience a drama are through reading it, watching it on stage, and watching film adaptations.