Version management in iTunes

I understand that there is no full blown version management in iTunes. Most users would not understand or use it. Usually, you do not want to stay on an old version by accident. Nevertheless, considered the fact that it takes, even for critical bugs, at least some days for a developer to release a fixed version, iTunes really should have the an additional feature:

The version used should be a per-device-setting. Maybe someone owns an old iPhone that can not be updated to an iOS newer that version 3.2 and an iPad that runs iOS 4.2. Some apps were released in a version that runs on iOS 3.x but later updated to run on iOS 4.x only. In these cases, one would like to have both versions in iTunes. Currently, if you update the app, you can continues to use the old version on the old iPhone. It is not deleted (or replaced by the not working version) automatically. But what, if you have to (e.g. after a repair) restore your iPhone? The old version is no longer in iTunes, you can not copy it onto your iPhone. That’s a undesirable situation … Apple, it’s your turn!