When you use C# and VB, you are using the full .NET
framework. But they have chosen to expose a smaller
subset of the API to developers to push the new vision
for Windows 8.
For me, this is a really interesting point that this article doesn't fully get. When you use WinRT you might be using the C# compiler, CLR runtime and .NET string & collection classes, but there are huge sections of the .NET BCL that now look like a lame duck. WinRT is the new way to do XML, JSON, HTTP, networking, security, globalisation, threading, printing... (more here: http://msdn.microsoft.com/en-us/library/windows/apps/br21137...)
You can still use the full .NET class library when doing ASP.NET, but who wants to use different JSON classes for App development vs. Web development? Won't the WinRT version gradually become the preferred way of doing JSON in both environments, with the .NET BCL existing to fill in the server side only gaps?
This is a really interesting question. I did some quick skimming over the docs there and even where there is conceptual overlap, the BCL wins in terms of feature breadth. It would be challenging to replace it, I think.
You can still use the full .NET class library when doing ASP.NET, but who wants to use different JSON classes for App development vs. Web development? Won't the WinRT version gradually become the preferred way of doing JSON in both environments, with the .NET BCL existing to fill in the server side only gaps?