Taking a purely personal approach to this question, I totally disagree with Wilde -- as I suspect he did too.
I have always lived a busy and stressful life, and have accomplished alot of conventional good things. However, some of the most important moments of my life have been when I am creating art. Fashioning clay into a human shape, making a beautiful book with fabulous paper and outlandish forms, capturing the expression of a face with a few quick strokes of the pencil. Art has been incredibly useful to me, bringing me closer to the deeper me and what it's all about.
Another example. Will.i.am's video about Obama moved SO many people. How could anyone say it wasn't useful?