Because it was a bad console? It had some good games but it just wasn't a good console to play them on. The UI sucked, it never had an achievement system, an account system, a friend system, a party system, a party voice chat system. Did it even have Netflix etc, I can't remember. It also always had the worst version of multiplat games (ie. the best games) if it even had them at all. The controllers were atrocious as well.
Bet Shiken that COD would outsell Battlefield in 2018. http://gamrconnect.vgchartz.com/post.php?id=8749702