My thinking for the last couple of months agrees with your paragraph in bold above. It's probably why MS is offering Win10 for free for one year. The hope being that folks will want compatibility across their phones, tablets and desktops. Apple has already got that right.It's obvious that Microsoft covets the mobile market and desperately wants into it. And I do believe that they've probably got the best OS offering that can span such a wide range of devices. I think it's a great platform - other things being equal I'd love to have the same OS on my phone and tablet as on my desktop. And I'm sure corporate IT departments would really prefer it too.
But the casual consumers that comprise the bulk of the market these days just don't seem to care about that kind of cross-platform compatibility. Perhaps it's because they're simply eschewing desktops and laptops altogether, so they have no apps and data from that world to worry about. What matters for most consumers is what apps are available and what their friends are using. Microsoft is locked out on both accounts. I myself had to buy an Android phone because none of my three remote controllable cameras have apps available for Windows. Microsoft rules the world for desktop apps, but mobile apps are an entirely different world.
It's a chicken-and-egg problem. Most people don't buy Windows phones or tablets because they're scarce and some of the apps they want aren't available, developers don't write the apps because there aren't as many people with devices to run them, and hardware manufacturers don't make the devices because of the lack of apps and customers.
My thoughts. Mileage for others will vary.
Sky