the point of not having a conscious theme would be just to entertain. 'theme' can be somewhat of a rather vague definition, i've found, often easily confused with plot. what you do mostly with a theme is say, 'i know something and i'm going to illustrate that for you now.' that 'knowing' may be something the reader doesn't agree with, so, for instance, if your theme is 'you have to have religion to be a good person,' don't expect me to buy five copies, lol. a lot of themes are just so vague or obvious as to not merit any particular, in-depth processes. 'friendship is good'... no kidding? really? wow. how profound. come up with that all by yourself, did ya? lol. i don't mean to pick on anyone, i'm just saying that's pretty lame, which most themes are. were there a list of the most obvious things in the universe and truisms even a five year knows about, i'm sure plenty of people would use those as themes for a story, if not a career.
a lot of themes are just personal opinion. 'A secondary theme seems to be emerging that men and women ought to be regarded as completely equal and sex should not have anything to do with reproduction, which should instead be based on two people having a bond of love such that each completely likes and respects the other and consequently they want to create a child who is a mix of them both.' sorry, s&s, that's hippie crap to me with no basis in reality whatsoever. i'm not saying it's bad or wrong, per se, just it's bad and wrong to me. it smacks of preachiness, almost. don't feel bad, though, i was just using that as a convenient example of pawning off the author's personal philosophy as a theme, which, for me, needs to more along the lines of truism-based reality. (don't get me wrong, s&s, i'm not attacking you, just the idea of using stories as a platform for one's personal propaganda is and always has been a repulsive practice to me, one which flourishes, so i'm clearly in the wrong here if you believe in the statistics.)
i just don't agree with a lot of people's 'themes' any more than i agree with their philosophy or politics. using opinion as a theme will probably be the fastest way to a niche market you could hope for. author's supporting their opinons, er, themes often only present those contrived facts and situations to support their own opinion. that is, a lot of authors aren't objective enough *not* to be spouting their ideals at every turn given the chance.
i get enough flak from spouting my opinion on MB's. imagine if i wrote an entire book like that, but with my ideals subtley hidden, lol. that's why i don't start off with specific themes in mind. it helps that i don't have to, either. if, in the course of writing it, one becomes apparent to me, i'll consider what it means in relation to the story and go from there, but i generally know what's going on before i get to writing so realizing a theme usually has little if any influence. then again, i don't sit down and plot which archetypes i use, that's just as awful for me.
of course, it's easy to get wrong what the writer intended. i had a star wars fan-fic up that someone reading could confuse with having all sorts of themes, but that's so not the case. the guy sacrificing himself for his wife and family wasn't a theme (which is really a plot point anyway), but just what the guy did based on his character. the protag was a stormtrooper, even, which wasn't even an 'evil isn't always as evil as it's perceived' thing. i just thought it would be cool, that's all. one of my high school teachers read themes into every third sentence. after awhile he just sounded ridiculous.
i suppose there's a lot of success to be had at jumping into a story theme first, though i think there should be some caveats to be aware of. for me, that's writing by numbers. *that's* when i ask 'what's the point?'