A lot of writers I know don't really worry about themes. They set out to write whatever story they want to tell, and don't give too much thought to symbolism or meta-concepts. Not to say their books don't have themes -- I suspect every story has at least one theme, and most likely innumerable ones -- but the authors don't put a lot of thought and effort into cultivating them. They prefer to cast the dice and let themes fall where they lay (not to mention mixing metaphors).
I'm not like that. I am hyper-aware of theme, to the point that theme dictates a lot of my creative process and most especially the way that I end books. Until I know what I want my book To Say, I rarely know how it ends.
Not that I'm setting out to write didactic moral-filled fiction or anything. I'm not really trying to change the world or blaze any new ground (although it'd be really cool if I did), I just want to make sure that I know what the implications of my story-actions are. I have too much background in literary theory and criticism to allow myself to be completely blind to the Underlying Message of my stories.
I spend a lot of time tearing apart the unfortunate implications of various bits of popular media, from books to movies and music. I suspect a lot of times the artist wasn't really thinking about what their story might be saying -- they just wanted to tell a good story in whatever manner they knew how.
Granted, you don't have a whole lot of control over what people read into your stories. There's always going to somebody who sees something there that you didn't intend. But for the most part, I think that authors do have at least a little control over what they're saying, and it's important to make sure your stories present a notion of the world that you can agree with.
I don't usually judge authors for their content. If your book is violent or depressing or full of sex, I won't think that you're an amoral person. But if your book seems to have a single theme or resonating message, and that message is disturbing....well, I can't help but let that color the way I think about you as an artist.
For example, a vibrant discussion of 50 Shades of Grey is going on over on QueryTracker. And one of the disturbing themes of the book, at least for some people, is "You should totally stay in abusive relationships; if the guy's rich enough, it doesn't matter -- and besides, you can change him if you just try hard enough!" This is, as TvTropes would put it, a "Broken Aesop," and it's the sort of thing I'd really hate to have crop up in my books if I can help it.
Of course, plenty of people read other things into it (like the attractiveness of the "alpha male" and how smut empowers women), which makes this whole "themes" business all the more difficult to nail. It's still important, though, at least in my opinion.
Anyway, all of this is why I'm currently in the throes of trying to find an ending to the upcycled novel/WIP. The old ending won't really work, and I'm having a hard time finding a resolution that's really satisfying -- both for plot reasons and thematic reasons. I've got a Final Problem, and plenty of solutions make logical sense -- but they'd all make for some pretty bad downer endings.
Anybody else out there hyper-aware of theme? Does it help or hinder your creative process? Any tips on figuring out a good ending?