I think one cannot construct the ideal user interface, store-owners must have an option of adapting the interface to their individual needs.
The ideal admin area in my vision would be customizable. Every merchant has his own individual workflow. Most common, the daily routine of running a shop is reduced to 3-4 actions. This actions must be at reach, ideally on the main dashboard side to side with statistics or one click away.
I think it is possible with some admin-area constructor. The merchant himself just drags and drops desired modules onto the dashboard without clicking other tabs and create his ideal admin area.
This is exactly what I was thinking would ROCK! Plugins or Widgets could have "tiles" for the Dashboard. Each Admin or Staff could drop in the tiles they want that they have access too. Also great for Vendors, Affiliates and another thing I thought may be nice is to also adapt the Admin theme to the My Account area or at least make it more current design and function.
That was my planned next phase on our Admin Theme which is only about 87% complete and now we have to decide what to do with...
Just my two cents on it. :)