It's certainly not just sci-fi writers who go for this sort of reasoning. I knew a theology professor who would make mistakes like this on a consistent basis. For example, he would raise questions about whether there was an evolutionary pressure for babies to evolve to be cute, without even considering the possibility that we might evolve to find babies cute. It struck me as being much worse than the sort of unthinking assumption that goes into Attack of the Fifty Foot Whatever sci fi stories, since his preconceptions were actually hindering him in fairly serious attempts to understand the real world.