It was built primarily to make complex "mega-menus" easier to construct and even easier to edit. Amending the content of the drop down is as simple as editing an article via the article manager.
Usually a drop down menu displays a list of links generated by the Joomla menu manager and displayed in the "unordered list" style. However this module displays "divs" of HTML pulled from seperate articles, allowing you to break free of the standard menu format. Therefore the layout in one column could be of a completely different format to the rest.