The two images above are both good examples of texture. The one on the right dosent have much. Though you can tell what it is and even though it has depth, it dosent look complete.. It looks as if  its a cartoon.  The one on the left almost looks like a poliroid. The wolf in the pic looks soft as does the grass..  If we were to look at a couple of the falling waters sketches I have posted on other pages on this site we would see that the walls and trees look touchable as does the water. Texture adds to the depth that you want to portray.