Apple is sometimes very strict about enforcing the way things were meant to be. With the number of apps using IAP for buying items within the game, I would wager that Apple meant IAP to be able to buy just about anything that exists within the app.
As I said in another comment - if you look back at how software licensing worked before the AppStore time, it's a long stretch to assume that Apple could foresee the current use of IAP, that's of purchasing small expiring upgrades for the apps. It's really a new and largely unexpected development.
Not really, pay to play gaming has been around for a lot longer than smart phones and the associated apps. However, it's questionable how much Apple tried to foresee what the future use of IAPs would be.
Before the first highways were built, I doubt people would have expected hotels and fast food restaurants to become an almost parasitic infection around off ramps, but they did.
It's often more about the idea than what the idea can do.