OS X/Cocoa includes some Emacs-style key bindings by default (see http://www.hcs.harvard.edu/~jrus/Site/system-bindings.html), so I don't think leaving other key shortcuts out makes the keyboard "interfere with a novice user" as you say. Dialog boxes don't support keyboard accelerators other than Esc and Enter, and the Finder doesn't support things like cut-and-paste or opening folders with the Enter key, and I find these things incredibly frustrating having used Windows in the past. Try doing something simple like moving a file from a directory to its parent in Finder versus Explorer.
Oh man, moving a file to its parent. You'd basically have to copy it, go up (I'm not sure if backspace goes up, does it?), paste it, find the folder again, go back down (or just back, i guess), find the file and delete it.
A clusterfuck, I can't fathom how some people can actually argue at length that OS X is fantastically keyboard-accessible.
I've used unix os's for longer than I have windows, I consider the terminal to be "keyboard-accessible". You can argue that point if you like, but the terminal is always a command tab away. That with osascript and the open command means i don't have much use for Finder. If I could keep Finder from restarting it wouldn't even be running on my system.
More on the "Cocoa Text System": http://www.hcs.harvard.edu/~jrus/Site/Cocoa%20Text%20System....