Objections about relevancy of curricula and objectivity of intelligence testing aside, we all need to be as adept as we can in using and interpreting these language symbols. Text requires effort to derive meaning and therefore is considered by some as dull, tedious and boring. The Internet is an important development of modern computing. Graphics represent the most important aspect in that development of modern computing. That's because graphical presentation represents the most effective and powerful means of communicating ideas from one human to another.
Visualization is inherently less abstract and more direct than textual language symbols.
One does not need to transform a set of abstract language symbols into an image. One observes the image itself. You could think of graphical visualization as the lazy man's mode of cognition. At least on the recieving end, the viewer can be rather more passive in the process of assimilating information. But the advantages far outweigh the pejorative implications of such passivity for at least two major reasons.