(Up until Aero Snap in Vista and it's keyboard shortcuts of Win+Arrow Key I used to use Alt+Space,M a bunch because it was always the easiest way to move any window by keyboard in the event it got stuck somewhere out of mouse range or you just didn't feel like switching to mouse.)
Also, most applications will actually honor Ctrl+C/V as well as the Ctrl+Insert/Shift+Insert shortcuts, from the 1987 IBM CUA guidelines[0].
Somehow everyone thought it was a great idea to copy them.
I change this in most of my window managers on Linux, but Chrome stubbornly insists on doing its own window controls.
Was it all a good choice? For some it was annoying. There was a shortcut that did the same thing. If you double clicked the upper left it would close the window too. Which is how they taught people to use win3x. Most certainly it was an interesting compromise to the constraints they had.
Copying the style was all on everyone else though. They wanted it to be familiar to windows users. All to 'gain market-share' I guess.