"If I sold a console two years ago and now it's in a closet collecting dust, that's not good for the gamer, that's not good for the developers, and frankly, it's not good for Microsoft," Spencer said. "The nice thing about us selling consoles is your console install base will always go up. But that's not really a reflection of how healthy your ecosystem is. We focus on the monthly active user base because we know those are gamers making a conscious choice to pick our content, our games, our platform, our service. We want to gauge our success on how happy and engaged those customers are. We need to keep them happy."
-Xbox boss Phil Spencer
http://www.gamespot.com/articles/xbox-one-sales-reach-26-million-report/1100-6447023/