Sigh. Yet another “the way I am used to is better” argument.
IMHO, maximize was a great concept when monitors were 800x600. Today, on my Mac, I never, ever, make windows the “full screen”. On Windows, when I make something “full screen”, what I really am after is a “no distractions” mode, like the “full screen” mode of Scrivener (the interface doesn’t fill the screen; everything not of the app gets faded out to a dark dark gray or black). In the end, though, the Windows maximized windows usually either hurt my eyes (all white, everywhere!) or make the app unusable (the buttons of the interface get flung to the far corners of the desktop, because I said I wanted the window that big and obviously the buttons must be anchored to their nearest corners).
In a “well-behaving app”, that mythical creature of yore, “zoom” (the OS X term for it) is highly useful. I don’t spend time “arranging” my windows; that’s precisely what the zoom button saves me from!
“Dealing with multiple windows is far too difficult, even for sophisticated computer users.”
As Nielson said in the quote directly above this: that is very true (for novice users) when most windows are maximized. However, I haven’t ever seen a user get confused about the existence of a window when they can see a statistically significant portion of it peeking out from behind their front window. Then again, I also don’t see users trying to tile their windows together like you appear to feel is necessary when multiple windows are on the screen either.
“Can you name one application with a multiple window interface that’s even popular?”
I’m not sure what you’re asking. Are you looking for MDI applications? I can’t think of any, but MDI was an abortion of an idea from day one; I don’t see what point that might begin to prove. Are you talking about applications that support having multiple windows open at once? Well, since you just mentioned Office, I’m pretty sure Word opens multiple windows, one per document. Are you talking about applications that are designed and work well in an overlapping-window mode? For that, I’d start looking away from Windows apps, as “Hit the maximize button” has far too long been Step 3 in the boilerplate Quick Start guides. Windows apps, by and large, tend to behave like they own the entire system, including all the user’s attention. On the Mac, though, apps which work great with overlapping windows abound.
All that having been said, the #1 most important thing with overlapping windows is that the “front” one needs to be immediately and clearly identified. OS X has tended to be movin in the wrong direction here for the last several years (brushed metal windows are incredibly similar between the focussed window and a background window), although even so the window shadows give at least a good subtle indication. Leopard’s window style seems to be a step back in the right direction there, thankfully. Vista has also made some significant improvements (especially over the Win 9x style window adornments in your screenshot!)
“Designers should be coming up with alternative user interfaces that minimize windowing, instead of forcing enforcing arbitrary window size limits on the user for their own good.”
I’m not sure who is being limited here. You suggested that fixed-layout windows should not be resizable above (an edict with which I completely agree). If you really want a window to be as big as your screen, you can drag the corner to be that big (or download a script to do that for you). I don’t even think Windows is imposing size limits here; they just aren’t giving the user a quick and easy way to “pack” the window to the minimal size the application wants. Still, the user can do that themselves; it just takes a whole lot more effort than the maximizing gesture takes on OS X.