Maybe it's because we as writers are alone so often, are so attuned to listening to the run of our own thoughts, that we find it more natural to write down the thoughts rather than the deeds of our characters. But speaking as a teacher who has spent some twenty years slogging through manuscripts where thoughts and exposition pile up as thick as the aftermath of a California mudslide, I can attest to the power of the evocative detail, gesture, or figment of speech.