Because 20 - 30 year old consoles have a long life in front of them. :/ :Spoiler alert, they do not:
Newsflash man, having non DRM copies allows you to do certain things with your games that you can't do when you buy them on a digital service. Like back them up and play them on your PC, or not having to buy the same damn game twice because a certain someone broke Backwards compatibility. Or even letting you reinstall in a pinch if you delete it and have Garbo internet
It might not apply to this particular scenario, but there are plenty of advantages to tracking down a physical copy. Which I now have to do.
The availability of lower selling games vastly improved because of PSN/XBL.
I know!
Let's go back to a manufacturing-based approach and just produce 100k units of the less popular titles. Slap a $20 sticker on remaining stock after six months and only allow enthusiasts on ebay to play them after that.
You mean like what I have to do right now? Golly gee! Digital releases sure helped me! I can't wait to employ this same tactic for Scott Pilgrim versus the world! Oh wait...