Originally Posted by Clocknova 
That may be true of iOS devices, but deleting a game from a Mac does not take the saves with it. If they're going to the trouble of adding cloud support to the Mac version, I have to believe that cross-platform saving is the reason.
Well, some Steam games also save to the cloud (e.g. Skyrim). This saved me when my hard drive crashed last week, so cloud saving is appreciated nonetheless.