Today the concept of literacy comprises many media. An enlightened policy of literacy must take into account the possibilities of all of these media. Educational preoccupation must be extended to the whole of media. Responsibilities and tasks must be carefully balanced. If for learning languages, tapes are better than books, take care of cassettes. If a presentation of Chopin, with commentary on compact disks, helps people to understand Chopin, don't worry if people do not buy five volumes of the history of music.
Even if it were true that today visual communication overwhelms written communication, the problem is not to oppose written to visual communication. The problem is how to improve both. In the Middle Ages visual communication was, for the masses, more important than writing. But Chartres Cathedral was not culturally inferior to the Imago Mundi of Honorius of Autun. Cathedrals were the TV of those times, and the difference from our TV was that the directors of the medieval TV --read: good books-- had a lot of imagination, and worked for the public profit (or, at least, for what they believed to be public profit).