Why are the uses of layers important in the production quality of a design in Illustrator?
Using layers in Illustrator is very important because it adds so much definition and shape to an illustration. Looking back at previous work I tackled (such as the cocktail drink), the use of layers for the glass and liquid helped give off the feeling of visual depth in having the object being 3D-like since one layer defined the light shining on the glass, and another layer defined the movement of the ice cubes and vice versa.
Collectively, when you take these distinct layers to produce an overall image, the resulting quality is a composition shaped by what visually pops out vs. what blends in naturally, which helps in truly seeing if an illustration has depth or dimension. This is a far cry from simple drawings that are mainly 2D in nature since they involve very few layers and not in the same manner as the projects that I am working on currently (like the city drawing requiring countless layers of small illustrated assets to depict the distinction between the foreground and background and the natural presence of a city stroller sitting on a bench; some of these layers have to be grouped even to allow for more control in designing a section of a complicated piece).