Lots of us really like the 2-in-1 concept and find it incredibly useful. Last time I bought a non-touch laptop, I quickly realized my mistake and took it back for a touch-screen model.

Otherwise, the long-term plan is to transition between the old Win32 API and the new Windows Runtime (which are both part of the same OS).

The transition to the UWP isn't going very well at the moment, of course, but Microsoft didn't know how it would go when it started. However, it's a long-term play so ask me again in 10 years.

If Microsoft hadn't made the move then it would clearly be a legacy OS. As it is, Windows 10 is a cloud-integrated, continuously-updated mobile OS with sandboxed apps maintained from an app store, just like iOS and Android. It just has rather too much of the old stuff hanging around as well...