The user is probably uncomfortable with full keyboard use, and will be selecting a menu item via the mouse (rather than hotkey)
As for an actual feature.. I feel the majority of the potential user-base would consider it jarring to have the cursor thrown about without their control
As for your request, I think it can probably be done via an external script and I would ask the people on the AutoHotKey forums
http://www.autohotkey.com/board/You may need to use the 'additional classic menu hotkey' option in classic shell, so they can 'forward' the key press to classic shell (because having 2 things on the same hotkey often causes issues)