It is so late because Microsoft has Surface pro which runs windows long time ago. It is funny to see Apple adding file app, drag-n-drop features as improvements.
While Microsoft is trying to pare down their desktop system while maintaining legacy code, Apple is able to add core features based on usage and demand. The iPad and Mac are like testing grounds for each other where both OSes can borrow good aspects from the other. Sometimes it’s easier to start from scratch and rethink the fundamentals rather than modifying existing ideas under constraints of the old paradigm.
Apple has MacOS already as a “fallback”. If Microsoft one day realizes that Apple’s tablet interface is the way to go, they would be seriously behind.
Under jobs, Apple has vision clarity, iOS was going to be primarily consumptive, and MacOS was production. The two were not to meet.
MSFT on the other hand had grown too many OSes to deal with capably, an example being that xbox, windows, windows CE all had their own implementation of TCP (iirc).
So MS decides to fix their architecture, unifying and ordering all implementations. It's a huge under taking.
Apple without jobs is meandering towards the same ideas. But iOS is not designed for these use cases. The iPad Pro and Mac OS will not converge. The best that the iPad Pro will become is a power android variant.
Microsoft will keep making surface and surface like devices, which will be not face that limitation.
If anything, Apple will have to imitate the entire Microsoft style, and include a touch screen on the mac, along with stylus support.
Their product vision is lost without jobs.
For actual work, selection, dragging, drawing - the arm/wrist do a very good job, better in more complex use cases than fingers.
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...
Which is why the market is still wide open.