[Gilpo]

Does it matter? Hmm. That's a good point -- it may not.

But ZAMM and Atlas Shrugged certainly felt to me a bit dishonest in that these works are primarily delivery devices for the authors' philosophical ideas. Other authors inject philosophy and ethics into their "straight" fiction, such as the philosophical rant-free work of Tolkien (LOTR = a treatise against fascism) and Stephen King (The Stand = a treatise against organized religion), but their philosophies never smack you in the face. [edit: grammar]

[Eliezer]

I think it's okay to smack the reader in the face with all sorts of knowledge provided you're sufficiently up-front about it, make sure there's more to the book than that, and give the other side a fair voice. (MoR!Dumbledore, MoR!Quirrell, the Lady 3rd Kiritsugu from Three Worlds Collide...)

I suspect that what goes wrong is not writing a philosophical treatise in the form of fiction - what goes wrong is that the One True Philosophy is treated as a Mary Sue within the context of the fiction.