You're lucky now with this particular set of games but this isn't guaranteed in the future. As developers we have the option to now choose whether or not a version will still be available after it's been pulled from the store. Naturally we can't stop physical .ipa's stored as a hard back up but I can imagine more and more developers will start using the perma-kill function for the cloud backups mainly to avoid future licensing issues (look at games like Crazy Taxi and Outrun 2 which are now edited to hell due to expired music and advertising licenses).
Long story short, if you love a game, back it up physically!! Although it wouldn't surprise me if Apple were to completely remove the non-iCloud backup option from iTunes sometime in the not to distant future.
That's why I don't trust the cloud, that's why I prefer physical games and consider download-only games to be a plague, because beyond downloadability there's a lot of other issues involved.
And pulling the download option for an already paid-for item doesn't seem like complying with licenses.
In the case of GTA SA for example what they could have done was create a separate listing with the remade version and pulled the old listing, but keeping it downloadable for those who already bought it.
It's not redistribution, the moment a game's in my online library with a service like Steam it's mine, and even the "it's just renting without an expiration date set" kind of philosophy Steam and others want lawyers and judges to believe in wouldn't hold ground as by EU law (or was it German law specifically, I can't remember just now) games in my Steam library are properly mine. They are not rented indefinitely, that's an invalid clause/state/whatever you call it.
Now, that of course doesn't mean they can't pull downloadability, but what I do mean is that the update to existing copies removing content actively (GTA SA patch) was actually against the law, at least here.
However, of course I agree, the download-only games you do have, you should backup.
And also hope that they will stay compatible and that the various ways DRM can bite you won't bite you.
I stopped bothering with games on iOS to a great extend due to that.
Glassed Silver:mac