Adam Roberts has a theory as to why Tolkien's novel is the fourth best-selling book of all time:
I stress the 'incompetence' angle in my retelling here because, really, that's what characterises the main players. It's an endearing incompetence, used partly for comedy; partly for dramatic purposes (by way of ratcheting up the narrative tension and keeping things interesting) and partly to facilitate the readers'—our—engagement. Because we can be honest; we'd be rubbish on a dangerous quest. We're hobbitish types ourselves, and our idea of fun is snuggling into the sofa with a cup of cocoa and a good book, not fighting gigantic spiders with a sword. Or more precisely, we enjoy fighting giant spiders with a sword in our imaginations only. The book has sold as many copies as it has in part because the Hobbits are able (textually-speaking) so brilliantly to mediate our modern, cosseted perspectives and the rather forbidding antique warrior code and the pitiless Northern-European Folk Tale world.
The Dish 