The importance of "Why" in User Interface Design

Sometimes clients feel they already know what their customers are like so user research and usability testing is not needed. Unfortunately, these clients often assume that they and their product’s users are exactly alike. At this point it becomes important to ask the question how do we know this about the users, and more importantly, why do the users feel the way they do? Why do they want the things the client believes they want? It’s one thing if users, for example, say they want more functionality. It’s another thing to explain and understand why they want it. It’s often in the “why” that real improvement and innovation finds its direction. User Research can answer the question of “Why,” as well as give insight as to why they are using the client’s product to begin with. “Why” allows for the challenge of existing paradigms and points to solutions derived from a solid knowledge of the end users mental model as well as other underlying factors.