I think the term "Art Rock" has become redundant and useless, not to mention too ambiguously broad.
It used to refer to the batch of post-Beatles intellectualized rock artists; everything from progressive rock groups like Genesis and Pink Floyd to The Velvet Underground and Roxy Music.
I just see Art as being a general human expression that we really don't have a right to call what is and what isn't art. Taking the time to arrange your flower pots in a specific manner is no less "artier" than a Rembrandt painting or a piece by Beethoven. Just like something like The Four Season's isn't any less art than Phillip Glass.