Some time ago I learned that Billy Joel has been busy composing "classical music." What this term means to composers of popular music is generally something quite different from what it means to modern, mainstream, "serious" composers. To most pop composers it means putting on a suit and a tie, at least figuratively or mentally, and behaving like stuffed shirts.
In Billy's case it means writing imitation Chopin — competently and agreeably, to be sure, as what I've heard is unquestionably pleasant listening, but is by no means innovative or challenging in any artistic sense. It also means that the millions of listeners who enjoy his superior and original songwriting are being deprived of new output in the genre in which Billy — a.k.a. "William" on the title pages of his classical works — excels in most.
Few composers of pop songs or rock and roll who have ventured into the so-called classical world have created anything of substance. The only composer I can think of who has been successful to any meaningful degree was Frank Zappa. I tend to believe, too, that if the superlative songwriter and movie composer Randy Newman were to take up writing concert music for orchestra or chamber ensembles the results would be interesting at the least and probably charming.
In contrast, in addition to Billy Joel, there has been Paul McCartney, arguably the best songwriter of the twentieth century, whose excursions into orchestral music with his Liverpool Oratorio and Standing Stone are unadventurous extended rambles, which for the most part he was able to compose only with the help of assistants with greater technical skill.
That many existing fans of these composers enjoy such work is no surprise. As one reviewer of McCartney's work illustrated, quoting from columnist Dave Barry, there are plenty of people who are happy to exchange valid U.S. currency for bottled water.
One must not criticize any artist for attempting to reach out in a new direction, for that spark of desire is at the core of the creative process. It is only disappointing to see some who have been successful in their primary calling travel instead down old, safe, and oft-trodden paths.