In other words, if I'm trying to free up space by deleting games temporarily, is there a way to save the game save data so that when you re-download the game, you can pick up where you left off?
Use iExplorer and copy the data file and then you can replace it when you reinstall the game to start at he spot where you left off when you deleted the game.
It would be the responsibility of the game developer to add such a feature, not Apple's. If it bugs you, ask the game developer to provide that functionality.
I use iexplorer or ifunbox. The savedata is usually in the documents folder but I backup everything just incase. Then when you reinstall the games just copy the documents folder back and you'll have all your progress back for your games.