Security. I believe Centennial apps don't have the ability to actually modify the system - they just think they can via the container interface.

Worth noting: the Xbox One has used virtualization since day one for video games. Done right, gamers shouldn't even have to know that this is what's happening. https://en.wikipedia.org/wiki/Xbox_One_system_software#Syste...

Disclaimer: Microsoft employee, not working on Windows 10 (aka I have no idea how accurate this is).