It's hard to texture dock well because of the way they stretch. Sometimes, it takes a great amount of time/work to get a texture to work, and then that's only at a specific icon size. You nudge the icon size up or down one pixel and it can mess up the look of the dock. True Stretch has helped out somewhat in this regard, but it still isn't perfect. That's why you don't see alot of textured docks.
