Well said, the reason Apple's OS is so stable is because they don't have to support "15 million" other devices and drivers.
Also, Apple is a very closed culture, maybe they don't want to share. A VP just left Apple, forgot his name, he was the inventor of iChat. Anyways, he says actually MSFT is more open to new ideas.
Finally, Steve Jobs is famous for being a control freak, as long as he is the CEO, it is unlikely he will license OSX to PC.