A lot of Art boffins claim that to be Art it must not have any useful serving function. By rule, design is built around rules and is useful to the user by making browsing easier.
i submit that painting and music are also goverened by rules. they are clearly art forms. the cutting of film for dramatic effect is governed by rules, and the cinema is an art form. and in at man cases, art is useful. its best exemplars serve cultural identity. they educate and broaden experience (the best artworks are not just objects, but experiences). i could go on...