There are examples of great design produced exclusively by engineers or scientists. The reason is because good design fulfills a need, and in industry these needs are often technical. When you throw in the needs of human beings is that things start to get weird. Some needs are subtle (how to you design an MRI machine for people that have claustrophobia?), others might seem ridiculous (say, redesigning the shell because the internals were redesigned, just to signify an upgrade).

Even then, I think engineers make great designers and even artists. Gustave Eiffel had only built bridges until he designed the Eiffel tower , Joseph Paxton build the Crystal Palace because he had designed greenhouses all his life. And so on, there are many examples of great engineers making the jump to design without much effort and great success.