Sometimes we work on websites that no one must see before the launch date.
Like in Joomla you can deactivate or put the website on offline mode when working on the website. This feature is VERY useful in Joomla and should be implemented in DW. As it is now I can't see any feature like this in DW.
When we use the unpublish function it doesn't inherit to the child-menus. And if it did the menu in frontend would not be visible.
Then again - the Joomla Site Offline feature is a useful tool.