I would really like to see this feature, too. I work on a lot of titles that are published as PDF and ePubs, offset printed, and then need to be made available in both hardcover and softcover via print on demand.
Having a single page for front covers is the most efficient way to get a consistent export for stores/websites that want the front cover only, and a three-page-spread with the spine as the page makes it easy to create multiple spreads based on an approved cover and quickly adjust the spine and other elements when printing with slightly different spine dimensions and/or full cover wrap.