"But is interface design wholly in the realm of art?" You're right, it isn't completely but every interface has an element of art. Interfaces exist in the art

"But is interface design wholly in the realm of art?" You're right, it isn't completely but every interface has an element of art. Interfaces exist in the art world as well, for example architecture and sculpture can be "used" as well as looked at. Business design introduces another wrinkle but I would argue it's impact should be considerably less. A consumer should have the same needs/wants as a "user". Speaking to your comment about conjuring spells .. I too grow weary of "swipe interfaces" that expect you to fondle the screen in order to discern how to navigate. It's very gimmicky and only had a place when the first touch screens were being rolled out. How that touch interfaces have matured it should be obvious (and no not a overlay instructional walk-through tutorial) how to use your app/website.