Fabulous question! As many of the others are saying, I think both are important and that, ideally, they are best used together, in combination. I'm honestly not sure which is a more accurate record of history- history is subjective and is told through the voices of the survivors. Both written words and visuals can overemphasize and place things out of context. Some authors/historians do a better job telling stories through visual art, whereas others excel with written words. How many times have I looked at a picture and have focused on something in the background or have noticed something that I didn't see before? I think the same can be said about written work. Also, I think that all of this can really depend on the audience- I'm a visual learner. Thus, I naturally get so much more learning from an image than I do a paragraph of words. Ironically, if I were to record history, I would do a much better job documenting with written words, not with visual images.
This novelist uses such rich details in her writing, I didn't need pictures. The better the writing, the less I need visual aides.