I think it is the diagonal movement or the freedom it evokes. I like how it draws the eye to the photo and then leads it to other elements.
Sunbursts on a Christmas layout? Why not? It represents Christmas magic.
The It's Christmas line has so many fun elements. I cut out the sunburst and used only a portion. I also cut out the Merry from a journaling card to use at my title.
A design favorite...the sunburst!