What: Allow workbooks (Dashboards) to be places into two separate projects by uploading a single workbook and creating a symbolic link in other projects that would use the same workbook.
Why: I have found that many workbooks can be used for several logical departments and they just want to view the same data that was already built for another department in a different way, or just to make it available to a different group under their project. The permissions applied to the workbook would depend on which project you accessed it from. Also, the ability to upload a full workbook and choose different worksheets and dashboards to show within that workbook would be an added bonus.
The reason for a single upload is that when you make backend changes, you often times have to upload to all of the different places you have it uploaded, and then it also can duplicate some data on the server.