"Unfortunately, IAP being 'optional' means that no one will ever use it"

I think one of the biggest issue is that Apple is trying to capture all of the revenue from the App eco system from a single function, the in app billing. Which is an extremely bad value prop for any large corporation, and also means a lot of big apps get to use the AppStore completely free.

I think Apple needs to do some shuffling in how they charge for the AppStore.