It indeed fails to give the proper benefits of a max window application.
I play the odd mmo, and love to play in a maxed window. Why? Because I can put other windows which partially obstructs the game window, while having the game window partial visible, active, and still max screen size with no annoying border. An example is a common mmo practice of running (or flying, or whatever) long distances. It is not dangerous, it is not really hard or require constant inputs. At least if you are a carebear like me and stay away from pvp servers.
So if I can see a little of what goes on, and can get sound from the game while it lacks focus (which I don't think DW gives), I can pretty much read something on the web while travelling. I will see/hear if I am attacked, get stuck behind a tree or something. Local knowledge to know there is no cliff to run off helps, though...
I would think this is somewhat relevant in DW, as you can have stretches where the game runs itself and you basically wait for an alarm to go off. I can manage now because i have two monitors on my gaming rig, but I think I lose the sound of the alarm.