That may be due to the fact that the little smile at the end of a sentence can look really self-satisfied or fake.
Especially if you were to dismiss any complainers by calling them elitists, and afterward tack a smile on the end of the sentence. Here, I'm being nice too! :) :) :)
It makes me look stupid, so it can only be a sincere smile. Or maybe I'm just stupid... Well to be fair, we're discussing the psychology of smileys.
I have a theory about ":)", that people use it when there's a discrepancy between what they say and what they think, through the same mechanism of humor (which is also about discrepancies). And so in general, I don't trust people who use it strangely. But now, they're all going to use :3... We're doomed.
:?|