This brings me to my favorite examples of the dynamic quality of artists and their work: Devin Townsend. He has gone from punk rock, to death/industrial metal, to rock, to downtempo/progressive/ambient/blues, and back to tightly produced metal. For a normal fan of music, his catalog must seem absurd, but if you delve deeper, it is revealed via interviews that he has multiple tastes and influences and what's popular may not always be what he is interested in creating. Strapping Young Lad was probably his most popular contribution, but then when he took a hiatus and finally came out with Ki, it indeed shook some people up who had only listened to SYL. Pussy music? Maybe. Excellently written and produced music? Definitely. So you see, don't be discouraged if the artist near to your heart steers away from what you believe should be the right direction. If they fail, they fail. But don't damn them outright because it sounds different from what you're used to. If you truly care about the artist, and their talent shines through, then as long as their skill is seen, it shouldn't matter how it is presented.
And I think that should be the only principle that guides the individual artist. Expression of the self through your chosen medium. There can be nothing else. In the words of Salieri in Amadeus,
"If the public doesn't like one's work. One has to accept the fact, gracefully."