Psychology...so technically I pursue one of those careers in between. Sure...you can go the neurology route, which is more or less the "harder" part of the practice, but even that requires some creative thinking and idea making as we try to interpret thought itself from blips on a map. It's (so far) impossible to pick out the movements of creativity in the mind.
On the other hand, therapy (which is more the art) requires a lot of empathy and understanding. You have to be willing to explore and understand the human condition with someone to effectively do your job. If you limit the interaction just to a scientific calculation of symptoms, you alienate your patient.
I'm interested in cognitive research on adolescent learning...literally interpreting how adolescents think and feel about their curriculum and what peaks their interest. This is next to impossible to do without some form of sympathetic observation and without acknowledging the cultural background of the person, which may include any number of arts to evaluate. Similarly, you do it a disservice by not cataloging and evaluating it on a quantitative level...balancing and equating interaction and curricula to reach the larger populous with the information we want them to learn.
Really...I need both to do my job, people.
Edit: Also...what is this "happiness" business everyone is talking about? Art is also used to express great sadness, anger, frustration...it is essentially a balm to our wounds in certain conditions. That's why there are a lot of art therapy programs. Art expresses emotion in a way that an inventory can't, and gives a nice view of the "Little Black Box" of the human mind.