(From henceforth I will use the abbreviations for the titles: The Magician's Nephew is MN, The Lion, the Witch, and the Wardrobe is LWW, The Horse and his Boy is HHB, Prince Caspian is PC, The Voyage of the Dawn Treader is VDT, The Silver Chair is SC, and The Last Battle is LB.)
Thinking of the atmosphere of the stories, it's as if MN and SC take place in a more mythical, thematic, and moral ground from the other stories. HHB has some of the deepest spiritual moments, too, but they're brief and the rest of its form is just an adventure story with lots of walking through the desert. Yes, LWW and LB (along with MN) contain the most recognizable hmm, analogies or re-imaginings, if you will, of Biblical stories, but LWW and LB are at the same time just fun fantasy stories. There are themes and imagery in there, but there are also sword fights and battles and fantastical creatures and talking animals and all that. MN and SC are more stark.
MN takes place largely in our world, which may also be one of the reasons it is less liked. And SC is, well, kind of depressing. It's all about characters failing to do what they're supposed to do and what they know that they need to do. They make it though in the end, but not without consequences. And seeing their failure I think reminds us of our own failures. Which kind of brings us back to MN, which is the telling of how evil entered the world of Narnia, as it did in our world. So in thinking of these things, I wondered if it is selfish to dislike MN and SC.
Do you see what I mean? LWW tells (among other things) the story of how Edmund followed the White Witch and then was saved by Aslan; that's a story of redemption, and forgiveness is nice to hear about. But MN and SC have characters who are good and who mean well but who still fail--and that's hard to read about because we know that we, too, fail. Yet shouldn't we be glad to read stories like this, reminders of how easy it is to fall back so that we can perhaps do so a little less often? Shouldn't we like MN and SC for what they teach us?
Ah, but there is the thing: we don't want fiction to teach us. We want fiction to entertain us. So that made me think of the meaning and rights of entertainment. For instance, I tend to say that I like movies for entertainment when I'm trying to avoid watching what I know will be a sad movie--something about war, perhaps. And yet I like movies like Amazing Grace (which is the story of how William Wilberforce fought to end Britain's slave trade--it has both sad moments and a message about fighting for what is right even when it is not popular to do so). So is it true that I don't want to learn anything from fiction? Not really. At the same time, I don't want fiction to be trying to teach me and yet I do want to be able to learn from it. Strange, yet I think that's how most people feel, if they think about it.
But I also wonder what is our right, as the reader or as the watcher, to demand from entertainment. Entertainment, by its very nature, is designed for relaxing. So it is our right to demand fiction that demands nothing of us but our time: fiction we can go to simply to enjoy imagining another place, another time, or another set of (fictional) people. That's okay. It's okay because there is also plenty of fiction out there to teach us things: we don't need it all to teach us. So if MN and SC are less popular because they're less fun to read, well, I guess that's okay.