I often hear people advise writers to write for themselves, and I certainly see why this would be important. It's about writing what they believe in, what they want to talk about rather than what everyone else is saying they need to write. But I wonder how many people do this faithfully, even when they choose to write against what has proven popular/successful.
The analogy I always use is an mmorpg (Massive Multiplayer Online Roleplaying Game) that I used to play. In the game, many people found that there were certain "specs" (basically spells or abilities players would pick at the sacrifice of others) that were highly effective when, say, fighting against other players.
These were called "cookie-cutter" specs, because they were nearly identical to one another and didn't leave room for creativity--but they were effective because they utilized the most powerful spells/abilities and avoided the weaker ones.
And I think books are a lot like that. There are things, plot devices or formulas, that have been very successful, and a lot of books go the route of using them instead of taking a risk with the road less traveled. And that creates a bit of a dilemma.
Some writers do write for themselves, but there are those that write for their audience. Their goal is to entertain the audience and to make them love the book, maybe even at the risk of writing something that has been overdone to the point of becoming a cliche. But fans love these stories. So does writing something uninspired that appeals to the masses make someone less of a storyteller? Or does it make him a good one because he puts his audience's needs first?