There are some people who simply won't play old games. I get that, and that's where a lot of the....controversy comes from.
With MS's design, they can essentially continuously re-release the same games over and over because you won't be able to play them otherwise. Sure games are being re-released all the time now, but you don't HAVE to buy them because you can still play them on some other medium (like their original system).
Some people though do like to play older games. I jump from system to system playing games I never got around to :/ ---for instance-- I went from Shadow Hearts 3, to Xenogears, to Xenoblade Chronicles, to Mass Effect 1 / 2, to MGS3, to FF7, The Dig, Planescape Torment, to Chrono Trigger, then to Radiant Historia...you get the picture..that's all within the last year and some of those games are OLD.