I wish there was a roll-eyes image for this post.
What are you talking about? Even if we bought into your exaggerated and godlike view of Middle Earth's complexity and creativity, what does that have to do with Narnia? How does transplanting one world's look and "creativity" into another serve the latter best? Christian allegory has absolutely nothing to do with this! (And for the record, Tolkien's books, nor the films, were exactly subtle either.) If you think LOTR's world is the only way to create a diverse fantasy world, well, that's just stupid.
Seems like most of you just want more LOTR from Narnia. I want NARNIA from Narnia. Middle Earth should stay in Middle Earth, I'm not sure why anyone wants it to spread.
The last thing I imagined for that world was a dirty world with subdued colors, and I certainly never imagined that the real world would be more vivid and alive than Narnia, but that's exactly what it looks like from the pieces of concept art we've seen and this footage. I don't know, I don't see how making the fantasy world of Narnia more dark, ugly and dreary than the real world is helping the story at all. It's like reversing the Wizard of Oz and having the real world be in color and Oz in black and white.