Emphasis on more subtle features of data often provides more insight than expected. Finding this balance between realism and subtle cues is a fine art and greatly depends on the data and what insight the viewer needs.
Quantized color palettes, silhouette edges, and warm-cold coloring are abstract non-photorealistic methods that provide significant insight and depth to an image. Combining these methods along with standard visualization methods can reveal detail unseen in conventional methods and can often reduce clutter.