I admit it seems as though there is little to gain, but it would be a more intuitive option. The Notes client has often been criticised for being less than user-friendly. I just feel that the File Management in the Admin client ought to be a little easier to use, hence this idea and my linked idea
A move involves creation of a new replica and deletion of the old one (IIRC) - more steps than is really needed when just renaming a database on the same server
Better yet, when running a rename of user(due to marriage/divorce or whatever) we should get prompted to ask if we need to change their mail file name, janedoe.nsf to janedone.nsf. Also that their email address get changed accordingly and the old one added to the alias/short field.