If the features 800+ syscalls can be put into 45 syscalls, why not make an operating system that has only 45 syscalls?
Then make the kernel modular.... and we've made a full circle in the OS design :)
Because much of Microsoft's licensing revenue is contingent upon continuing to support the edge cases that are inevitably not part of the set of programs that can be dropped into such a sandbox without problems.
[1]http://arstechnica.com/information-technology/2014/04/the-in...
NT is sometimes mistaken for a microkernel partly because of the graphics driver problem, and partly because it contains a module which Microsoft actually refers to as "the microkernel". This part consists mostly of the scheduler.
What is true about the NT kernel is that it's modular, with strict internal API separation between each subsystem, and that kind of design was (as far as I know) inspired by actual microkernels, as was the idea of hiding the kernel behind "OS personalities" such as Win32.
While NT is not a microkernel, from a kernel API level it appears to basically be one, only missing the fact that everything is not actually isolated.
WinRT is COM based, similar in concept to Ext-VOS, the percursor of .NET, before it got folded into .NET.
http://blogs.msdn.com/b/dsyme/archive/2012/07/05/more-c-net-...