Have you used a Mac more than once? Or have you only ever used OpenDoc or something? I don't mean to be insulting, but nothing you describe happens or has happened in any Mac OS:

1. Mac apps don't have toolbars (save the odd cross-platform exception). App windows can have toolbars, but they remain with the window, so it's impossible for you to close a window and still work with its toolbar as you describe. Likewise:

2. "The Macintosh Operating systems have always operated under the assumption of single app focus reconfiguring the toolbar" can't be true, because there aren't any. The only thing that changes from app to app is the menubar, and floating palettes if there are any. They of course, disappear, so:

3. "with clutter from unfocused apps taking up the visual space." can't be true either. When an app's in the background, only its document or other main windows remain -- and you've already conceded it's important that they be there. All floating palettes and other "clutter" disappears (so you certainly can't be confused that it's the active app and try to use its invisible toolbars, either). If the main windows disappeared too, how would you support drag-and-drop etc?

4. "But my OS isn't trying to reconfigure itself to support whatever app happens to be in focus at the moment." ... and neither is Mac OS. There's no reconfiguration going on. The menubar titles change to accord with the active application, and ancillary palettes -- windows that only make sense when their application is active -- disappear. That's all that happens when an app focus changes.

4b. Which makes "and got supremely frustrated that I couldn't bring that app in focus" bizarre. You clicked on an app's window and it didn't come into focus? Why not?

5. "The disassociation of tools (methods) from the thing that you are working on (objects) is not only a poor abstraction, it's a usability nightmare." ... well, except that this is how we've worked every since our ancestors got tools? The hammer doesn't stick to the nail, or the saw to the piece of wood. Tools aren't associated with the things they're working on.

6. ... well, except in computing, where they are associated, necessarily. If you're working on an image, you're in an image editing app, and the appropriate tools need to be available. When you switch to a text document, they need to go away (as they do on the Mac), and document-editing tools need to be available.

7. All of this adds up to make your toolchest metaphor totally nonsensical. In what way and by what behaviours does Apple's metaphor mix up the buttons from your calculator with the pedals from your car? The only way I can make sense of it is to think that because the calculator is still visible on the screen while you're in another app, you're somehow confused about what you're doing. It's as if you want the OS to only allow you to do one thing at a time.

8. Which would be the full-screen thing. Except that breaks the metaphor again. It's a desktop. You're allowed to have more than one thing on it at a time. You don't push everything off your desk and only have one piece of paper allowed on it at any one time, do you? So why should your computer behave the same way? Especially if you've got a 24" or 30" screen. But, even then, you can just "hide others" and hide the dock, and your window can fill the screen with no other nasty apps insulting your field of view.

I'm sorry if we've got here from what you meant to be a throwaway line about the "multi-window aspect" of Macs, but really, unless you're making an argument for having nothing but old-school Windows MDI, it was a daft position to take, unless you've got a huge misconception about how Mac OS window handling works. It's certainly not "almost unusable" because it lets you see other windows -- and you've already conceded it's important to be able to see them, so I'm struggling to get where the "madness" you talk about comes in.