Have you seen most M.D.'s handwriting? Jokes and assumptions on your part (about me) aside, it just doesn't fit into the original purpose of the STEM acronym. Most scientists, Tech majors, Engineers, and Mathematicians are crazy creative. Real world problem solving requires creativity. Many pieces of software used to make jobs across the board were written by incredibly talented people. Architects have always been expected to have art/design skills. Art is such a broad field, you would first have to define art, and explain why it fits. Not all areas of art WOULD fit. Then who do you leave out? Not trying to gate-keep. Just doesn't really fit, imo.