suitable user interface for each application

Well, they're half way there...

Microsoft have noticed that trying to run a desktop UI on a phone or tablet is a disappointing experience.

Just need them to notice that trying to run a phone or tab UI on a desktop is a disappointing experience ;)

Maybe there is a UI able to straddle that divide - Metro isn't it. What's certain is they'll keep trying to impose Metro until its certain they own all OR none of the tab/phone market. Sense can only return to the PC versions when the PC stops being a trojan into the tab+phone market.