??Halo 2 Download??

So I have a serious question about Halo 2. Forget about an anniversary edition or anything like that I would really like to know why it is not downloadable on X Box Live yet. I mean after all CE was downloadable even before its anniversary edition came out so why not Halo 2? I ask this because even though the older 360s’ are able to play the game the newer 360 slim cannot and every time I have put the game into the system it says I need a download but there is no download! I just want to know if Halo 2 will be available for download at all any time in the future.

I would also like to know who agrees with me.