I mean sure if you want it to be art then it can be. But that's not typically its primary purpose. And the skills required to make a UI good for its primary purpose (usable, easy to understand, etc) are quite different from those required to make good art.

In other words, a UI as an artifact might be art. But UI design as process is different to the creation of art as a process. You could do both, but they're mostly orthogonal.