You can spend a lot of time applying the right textures and appearances in Creo Parametric, but when it gets published to Creo View, a lot of that is lost because it strips away the bump map information. Rough surfaces look smooth. Shiny metals look dull. Wood grains disappear. These are all from the built in appearances from within Creo Parametric, nothing custom. Creo View should be an accurate representation of the model, so it should also include accurate textures and appearances.
In this image, the one texture that appears in Creo View actually has a texture image. The others have only a bump map. I'm not even sure how the wood grain works, as it doesn't specify either, just that it's oak (it's the mahogany appearance), which has some built in meaning.