How important is context in literature?

Animal Farm by George Orwell is a great tale of revolt, idealism and ultimately the corruption of power. To the casual, uninformed reader it appears to be a face value story about a group of farm animals who overthrow their farmer with the intention of establishing an ideal society, but it finally results in its descent into a situation much like the one that they were faced with at the beginning of the book. A ten year old is perfectly capable of grasping the morals and characterisation of the story, although they are blissfully unaware of its intended parallels with the Russian Revolution. On second reading an extra dimension is added as similarities in the characters in the story can be seen with the major players in the Russian Revolution itself (the pig that puts forward the idea of the revolt at the beginning of the story clearly represents Karl Marx, the brain behind communism, for example). Undoubtedly this extra knowledge widens our appreciation of the book, but has it necessa...