Who would be so stupid and learn-resistant to use C# a third time for games?? Well there are those sheeps, that believes and do everything for their PR department.
http://news.xbox.com/2016/03/14/letter-chris-charla-idxbox-u...
XNA was a victim of the usual internal wars between Windows Dev and DevTools R&D units, about which way to build software (.NET vs C++).
Hence why they are so supportive of Unity nowadays, which is the main way to develop HoloLens applications.
the reasoning behind it doesn't change the years of my life I spent learning an obsolete tech stack.
which is fine: tech moves on. Except for the fact that MS told me it was the future.
and I don't blame them, but I'm also not going to take them at face value again.