The success of the products we design can often be affected by their visual appearance. In addition to the visual appearance, the cosmetics of plastic a part impacts the tactile feel. Quality judgments are often by how a product feels when we hold it or touch it.
In product design, cosmetics must be traded off against other factors like strength, durability, function and cost. For internal parts, cosmetics should be weighed less than other, more operational characteristics. For external components cosmetics may be a primary consideration.
The cosmetics of a part can contribute to both function and esthetics. For example, the color of a part might be chosen for safety reasons as well as for its attractiveness. The texture on a handle might be chosen both for its looks as well as how it improves the feel and the grip.