The Admin template helps you to understand better an administration panel.
I do not understand why do you worry about admin themes this much because waste a time, no body looks at your admin page even if you had a best admin design in the world so why can you not add and create more xhtml, wordpress themes.
Please please stop this waste admin page design and show us some good design, themes etc..As a buyer never looking to pay for admin themes by the way
The new concept of web 2.0 claim to use a good design for those admin sections, is better and easier to administrate. A good example is the cPanel Theme use in the web hosting control panels (eg hostronica.com) the template design makes you work easier with that control panel.