Hard to do, harder to learn
Good visualisation has a *huge* effect on how *quickly* and *effectively* information can be conveyed, whether it be using shading and borders in tables or more sophisticated devices.
While Visio is enormously capable, it takes a very long time to learn. I've used it on occasion, and always wondered if I was really using the right part of the program and the right templates. There's just no guidance, since Microsoft assumes (as always) that everyone knows what it decides to call things (eg: types of diagrams). This is a huge obstacle to widespread use.
Visualisation is also really hard to do well. Not many people have the knack -- think of all the atrocious PowerPoint presentations you've seen.
Finally, the real aim of visualisation is, I think, to provide additional data (sometimes in the form of visual context) much more quickly than can be achieved otherwise. My favourite example is the run-rate charts used during the cricket coverage. In order to properly interpret the data, it's necessary for the viewer to first look at the scale on each axis, as it changes during the match. If they locked it in, so all 50 overs were always shown, and horizontally, there were heavy rules every 6 runs (per over) and light rules every 3 runs (per over), within two or three viewings, we could interpret the entire graph at a glance without reading a single word!