Bookmarks are only possible in Data View, not in Layout View. The cartographer works in the Layout View and sometimes he want to save a specific place of the map. He use the bookmarks to save all difficult places for a discussion or presentation.
I like the idea. Until then you would have to bookmark the "layout extent" before zooming to other areas to ensure you returned to the same extent in the layout view. If you have a feature grid, and Production or Defense Mapping, you can also use the Grid Layout View tool to return to the original layout extent.
