Tight integration between a mobile phone and a desktop OS is IMO a misfeature. Based on your two examples it seems as if you feel this way because you've only

Tight integration between a mobile phone and a desktop OS is IMO a misfeature. Based on your two examples it seems as if you feel this way because you've only experienced light integration or poor integration, and don't have the imagination to see past that. If Microsoft can make it work, and offer something polished in the process then it could be something special. Remember they're counting the "desktop OS" of Windows as their tablet OS as well now. There exists untold numbers of opportunities for nice little integrations done well. Consider too that for most people in the developing world, a mobile phone is the only "computer" they will own. Requiring integration with a desktop PC effectively cuts Apple and Microsoft off from a market of billions of people. That's why you don't make it mandatory like you're suggesting.