>>44
First of all, we aren't writing an operating system. Second of all, an operating system is first designed to work as it should. It then becomes ``usable'' when there are enough drivers and user level code to make computer running the operating system provide for the wants and needs of the user. This concept of usability does not intersect with the stability, or any other aspect of the operating system's design. This issue is more or less solved with a compatibility layer for user level code and drivers. Then you can leverage past work while providing something new under the hood.