Lets us choose if we want the dirt in the planter or not because the planter could be used for much more than that I use it for a modern bathtub but because of the dirt I need to place a ugly canvas picture of water. I wish I could remove the dirt and then make realistic water with the new advanced canvas materials.
Or just remove the dirt from the model. If I want dirt in it, I can use a canvas to achieve it. Might be the simplest way to achieve the most versatility.