From reading the responses, I think it is safe to say that the majority of us don't come for the "warm-fuzzy" feeling of being appreciated. Many are IT professionals (such as myself) while others may be end users looking for answers and offering a little assistance. I, for one, enjoy the fact that I have helped someone at one time or another. There is a personal satisfaction in knowing you have helped someone. Certainly there are those that "lurk" seeking solutions to their issues. While you may or may not have helped the one that rejected (or just left the answer unrated) your answer, someone else just by reading your solution may benefit. I know I have.
It's annoying to be rejected out of hand, too. But, like I said, I doubt many of us are here for that "warm fuzzy" feeling of appreciation, however nice it may be to receive a simple "thanks, that helped" or whatever. Rather, we are in an industry to help people, share knowledge and learn ourselves. THAT, my friends, is why we come here, at least in part.
I've run public forums in the past. In some cases, anything you say will open you up to ridicule or "flames," as it were. Even on some Tech forums, that is the case. TechRepublic seems to be pretty tame by comparison.
Granted, there are those that just take, take, take without any regard for others. I like the one example about being cut of in traffic. Then once in a while, you will run into someone who waves "thanks" for letting them in front of you. Its that one that actually makes all the negative pale.
I think the stats are kind of an ego booster of sorts. The number of accepted answers compared to rejections. There is a sense of gratification knowing (and seeing) what help you have actually provided.
Despite the disappointment in rejections, consider that you have made SOME difference for someone. Better to make an effort than no effort at all.
Just my 2c