I think from the outside it's easy to interpret this as confidence or even arrogance. I don't think it is. It's just that...look, we already have people who aren't me, all right? And some of them have written books that are really excellent, and some of them have written books that are better than anything I will ever do. Do I want to write gorgeous books with stunning insights and gripping plotcharacters and images that haunt the reader for days? Yes, of course. But if they're not mine, why bother? If it's just like someone else's, why not just read that someone else's in the first place? So I don't want to write like someone else. I want to write the best books I can write -- the best books I can write, and if they're no good, they will at least be no good on their own reconnaissance. There will almost certainly be things about them that make me cringe later, or things I wish could have been different (because some flaws are inherent to the story at hand; some flaws are not just unfixed but unfixable). But it wouldn't work to be someone else anyway. It would come out funny, so I'm just better off being me instead.
If I pretend I can tan, I get an extremely painful sunburn and then go back to being a very white white girl. So I put on my sunblock, and I write my own books.
(Writing in someone else's world or writing a pastiche or parody does not count as not writing one's own book. Dumas could not have written The Phoenix Guards, and no two shared-world stories are interchangable.)
I also said: When I have something to say on a conscious level, it's almost always a very specific personal message. I wrote two novels (and have two more outlined) just to say, "I'm right here" to someone. I wrote a novelette to say, "Cut it out!" to someone else. And a short story to say, "I'm glad you're still around" to yet another person.
When I'm thinking about theme, it's usually "what do I want to poke and crumple and squish and maul" or "I don't know what I think about this; I'd better write a book, or, better, a series."
I think this may be about me writing from character relationships rather than from theme or even character or plot.
Unfortunately, "I'd better write a book" is something of a panacea in Mrissaland....