The Shell is designed in order to minimise distraction and interuption and to enable users to focus on the task at hand. A persistent window list or dock would interfere with this goal, serving as a constant temptation to switch focus. The separation of window switching functionality into the overview means that an effective solution to switching is provided when it is desired by the user, but that it is hidden from view when it is not necessary.
The popularity of Mint 12 with MGSE may be an excellent barometer as to weather users prefer a Task Centric or Application Centric desktop.
"I have just one word for you, my boy...plastics." - from "The Graduate"