I think this is a unix&mac vs Windows question...
IMHO Unixes are generally unusable with only one screen open or one fullscreen application. This is most likely a consequence of being an academic, mostly user build, OS where users tend to be working on many different things at the same time. Unix has always been a multi-task OS. Note that unix users historically tend to buy the largest screen available within their budget, often spending more on the screen then the computer.
The same kind of applies to the Mac OS X, only to a lesser degree. It's not unusable like other unixes but it tends to works better when none-fullscreen and it does not really have a simple "fullscreen" function in most apps. Only the bigger single-function apps (powerpoint, Garageband, keynote, etc) tend to take up a lot of screen space, which can be full screen on a smaller screen. The Mac is designed/marketed most successfully at the digital professional user who gets to decide what he/she is going to use. These users tend have quite large screens.
On the other hand Windows seems to be designed to be single task/use only. This is all due to it being in essence an enterprise OS, marketed mostly at the IT department not the users in the cubicle. To a long time unix user like myself all the apps seem greedy and want to take the whole screen whether you want it or not. In Windows full screen just works better. Windows users, especially in the cubicles, also tend to have smaller screens then unix or mac users.
And let not forget the ultimate full-screen applications: games. The single-task preference designed into Windows make it a much better Game OS then any unix (incl. Mac OS X) ever could.
I think that people who grew up with Windows or use Windows often will have learned to work in full screen mode, while unix users (and to a lesser degree Mac users) tend to use apps none-full screen.