I understand the reasons (sort of *1) for rewriting the compilers for C# and VB.net in C# and VB.net respectively (personally hope it the opposite way round. C# in VB.net  and VB.net in C#, as it'll end the arguments.)  

 *1 I understand it is written in unmanaged c++, Why not use C++/CLI?

@felix9:  That's point I'm make felix9, it's purpose is not obvious. 

"... but at least it will empower the framework builders/library writers/tooling providers to create super powerful and flexible stuff ..." 

How? This has yet be shown. (Even conceptually.)