Good point. Although maybe we should be somewhat more sympathetic to the authors - it probably is hard to write really intelligent characters, particularly characters that are smarter than they are, without it coming off as the plot bending to their whims.
I think it is hard. On the other hand, I think a lot of time people write characters they think are intelligent, when really they're no such thing. It would be easier to write intelligent people if they let them make some mistakes and wrong guesses and gradually get closer to the truth, instead of just putting everything together at once or in some great blaze of revelation.