They make a product's operation more intuitive to the user. They make the user of a product more at ease, thus reducing human error during use. The benefits one can quantify include increased comfort in seating, reach zones and intuitiveness of operation. Such intuitiveness can give the user a sense of control and immediate know-how. It can improve a sense of familiarity with a product and create ease.
More benefits are aesthetics that calm and colors that soothe.
To design for the human body, our profession must first understand how it thinks and works. Human error stems from interface problems. When a product is designed in a manner that is inconsistent with the way people think and operate, problems ensue. This can lead to product misuse as well as user confusion. Users may make faulty decisions or misinterpret data.