I read an article a while ago (by a horror/SF/fantasy author I respect) on the absence of three-dimensional characters in hardcore SF. He claimed that it was because the premise of the dystopia/new world/experiments/technology that took centre stage as the "main character" in the work, and that characters were more there to help carry out the plot and illustrate how the premise would unfold in society. He suggested to try and avoid that, for obvious reasons, but he did say that SF fans tended to be more forgiving of one-dimensional characters than most genre fans.