In The Lion, the Witch, and the Wardrobe, human beings and other creatures are at their best when they live in harmony with the natural world and do not try to halt the passage of time or arrest nature in any one particular state. When the natural world is allowed to progress in its own way, it will become a paradise, and very little will need to be done to make it habitable. Radical reshaping of the world in order to make it "civilized" or "modern" is highly undesirable. Everything that people need can be found in nature if they know where to look for it.
In order to restore the government of Narnia, Aslan must first reinstate a natural progression of the seasons.
The importance of having Christmas during the winter in Narnia symbolizes the importance of balancing natural rhythms with man-made ones – the seasons must co-exist with human ways of marking time.