This was, more or less, the driving philosophy behind BeOS. Therein lie some lessons for the prospective OS developer to consider.
Say what you will about how terrible POSIX is, Be recognized the tremendous value in supporting POSIX: being able to support the mounds and mounds of software written for POSIX. It chose to keep enough POSIX compatibility to make it possible to port many common UNIX shells and utilities over, while Be developers could focus on more interesting things.
So where were the problems?
One huge problem was drivers, particularly once BeOS broke into the Intel PC space. Its driver interface and model was pretty darn slick, but it was different, and vendors wouldn't support it (take the problems of a Linux developer getting a spec or reference implementation from a vendor and multiply). This cost Be, and its developer and user community, quite a bit of blood, sweat, and tears.
Another big problem was networking. Initially, socket FDs were not the same thing as filesystem FDs, which had a huge impact on the difficulty of porting networked software over to BeOS. Eventually, BeOS fixed this problem, as the lack of compatibility was causing major headaches.
The lesson: if you are looking to make an OS that will grow quickly, where you will not be forced to reinvent the wheel over and over and over again, compatibility is no small consideration.
Which points to what ended up happening with BeOS: it became an internet appliance OS, and then the core of a mobile product. These were areas where the hardware and application spaces were quite constrained, and BeOS's competitive advantage in size and performance could be leveraged.
Say what you will about how terrible POSIX is, Be recognized the tremendous value in supporting POSIX: being able to support the mounds and mounds of software written for POSIX. It chose to keep enough POSIX compatibility to make it possible to port many common UNIX shells and utilities over, while Be developers could focus on more interesting things.
So where were the problems?
One huge problem was drivers, particularly once BeOS broke into the Intel PC space. Its driver interface and model was pretty darn slick, but it was different, and vendors wouldn't support it (take the problems of a Linux developer getting a spec or reference implementation from a vendor and multiply). This cost Be, and its developer and user community, quite a bit of blood, sweat, and tears.
Another big problem was networking. Initially, socket FDs were not the same thing as filesystem FDs, which had a huge impact on the difficulty of porting networked software over to BeOS. Eventually, BeOS fixed this problem, as the lack of compatibility was causing major headaches.
The lesson: if you are looking to make an OS that will grow quickly, where you will not be forced to reinvent the wheel over and over and over again, compatibility is no small consideration.