All you have to say to understand why Microsoft is going this way is two words - Internet Explorer...
the crappiest browser on the planet made by a company that has billions. Next is "Microsoft Word" but I am redundant.

I worked in the Microsoft world for over ten years (classic asp then .net MVC and now have gone the way of open source, WordPress, php and Ruby. Why would you want to port over WordPress to .Net/C# is beyond me. Learn a little php! If you want to read a great book about this subject, read http://www.amazon.com/Success-Open-Source-Steven-Weber/dp/0674018583