During the Great Depression movie ticket sales skyrocketed (they didn't have TV back then) because, being miserable, people sought escape from their troubles in fictional worlds. Technology may have changed but humans are still the same in their preferences and needs.
With people being displaced by a lousy economy and seeing devastation in other countries and simply being depressed it stands to reason that a good, escapist show would do well in the ratings. It's more than telling that SGU is dropping like a stone in such troubling times.