Code design and the science of pleasure

As Rails programmers we talk a lot about the beauty, not only of the products we build, but the code we write. Why is this beauty important? Can we think systematically about the emotional effects of the code we are writing?

Code is meant to be read and used, not just by machines, but perhaps even more importantly by people. How people are affected by the products they use has been studied extensively in the field of industrial design, can we apply these lessons to the code we write?