I thought the same thing at first, I havnt been able to find an image of the moon after the pilot episodes but if the Mare is still there. (which just makes for a better looking moon) Then I think a possible explanation is the banishment of Luna's evil side, Nightmare Moon, back to the moon when she was blasted by the Might Morphin Friendship Ponies. x3
I absolutely love the idea of the sticky glowing stars thingy, and the second I read your comment about what they were, my mind currently being stuck in analytical literature mode, I thought that it isn't the darkness of the night itself that Luna is afraid of, but rather the incidents that the darkness of the night has caused. It is not lack of light, but the dark emotions she once held that she is afraid of, and the stars are representative of those who free her from the dark. Both the stars that released Nightmare Moon from the moon and the ponies that brought Luna back into the light. The stars are there to remind her of those who protect her from her own darkness. The stars remind her that despite being physically alone she is not alone.
The stars, her stars, her friends, keep her darkness at bay.