I'm not confusing it. I'm just not assuming the authors motivation was anything other than what was written. Do you have any hard evidence for the motivation?
Let's start with the low-hanging fruit: I assume that you accept that George Orwell's Animal Farm is a critique of Stalinist Communism, and not just a fairy-tale about some talking animals. And that Snowball = Trotsky, Boxer = the working folk of Russia, etc.
Then let's move to something slightly less literal: I assume that you accept that JRRT's treatment of Feanor (including his temptation by Melkor) and of Numenor (including the temptation of the Numenoreans by Sauron) is his reworking of the Fall.
More generally, I assume that you accept that authors sometimes write works to convey ideas and to reflect on themes and concerns that they don't expressly put into the mouth of any character, or the ominsicient narrator. DL is not as transparent as Animal Farm, but it's not the most subtle set of novels ever written!
In any event, in understanding why Raistlin can't create, and why
evil is not a creative force, in the DL novels, we are not confined to asking that question from an in-fiction perspective. We can ask it
as readers - and we ask it of the work itself, and/or of the author (depending, in part, on our broader conception of where artistic meaning is located). There is a whole set of disciplines devoted to this - literary criticism, musical criticism, etc.
It is largely from those disciplines - especially critisim of literature and film - that we get our critical vocabulary for RPG settings, given that there is no independent discipline of RPG criticism. (The Forge tried to establish such a thing, but remains a bit fringe.)
When I say "My character's morality is like Batman's," that's a meaningless statement at this point in time. It tells you nothing about that character's morality.
When my DM says "Let's play Dragonlance!", how meaningless should that statement be? How much should it tell you about the heroes and conflicts and villains?
<snip>
At a certain point, one needs to stop putting paint to the canvas and call it "done," warts and all (typically for written works, this comes in publication).
I still feel that you are assuming that even a single campaign book, or The Dragonlance Chronicles, bears a self-evident meaning that the actual experience of human encounters with works of art suggests it probably doesn't.
Eg I read the original DL books quite differently from Maxperson, apparently. I'm guessing the same is true of the two of us in respect of REH's Conan stories, and LotR and JRRT's other Middle Earth works.