While I think the argument here is interesting (that is, whether Apple is morally in the right to demand a 30% cut of not just the initial application price, but ongoing subscription revenue as well), it is also moot. Apple can do what they like and there is nothing illegal about it. If you don't like the thought process, better go get on Android before Google comes full circle and begins implementing the same controls.
Of course Apple can do whatever it wants here. App Store belongs to Apple. As much as Google can do whatever it wants with Google Play and Microsoft, with Windows Store. It's up to developers to accept that or not. You may, of course, raise several moral and legal questions on whether this is acceptable or not, but, in principle, there's nothing wrong with that.
That said, what I can not understand is your statement. You are, in affect, asserting that no large company would be willing to give up 30% on the sale price of a large item to a 3rd party.
Not exactly that.
The 30% Apple charges from developers is a large chunk. For small developers with a virtually unknown application, that's OK, because, if the app becomes successful, it will owe Apple a large stake of its success. The App Store is a platform for distribution of apps that also works as a platform for showcasing them.
Microsoft has a killer app, which is Office. It's a killer app because it's a worldwide standard among business and consumer users alike. Everybody uses Microsot Office, and to have the ability of reading and writing Office files is a must-have for any user.
Microsoft doesn't have to develop an iOS version of Office for it to become successful or even to maintain its hegemony. And Apple doesn't need Microsoft Office for iOS to be wildly popular. However, both companies could benefit from offering Microsoft Office to iOS users. Microsoft would expand Office user base even more, and would kill any alternative for iOS devices. Apple would make iOS a credible offer for business productivity. I could even say that this partnership would be even more beneficial to Apple than to Microsoft: people are already committed to Office and can't just give it away because of legacy compatibility; the iPad, on the other hand, is a neat device that can be immediately replaced for any better device that appears on the market.
There is no point for Microsoft in selling a full version of Office for iOS while giving away 30% to Apple. Microsoft doesn't need App Store to market Office; in fact, one could say that App Store is desperately in need of Office, or of a real, credible alternative (you may see at App Store that a lot of people are fooled into buying Office tutorials and manuals thinking it's the real thing - that's how bad people want it).
That is comical in it's error, even by internet standards. Each and every major development company (Autodesk through Vmware) all give up far more than 30% every day on practically every sale. In fact unless you bought it right from their own web store on their own site (which many companies won't even do), then the reality is that 30~50% of your money did _not_ go to the people who wrote it.
Well, Microsoft doesn't. Microsoft has a killer app which can't be easily replaced, not even by free apps such as OpenOffice or LibreOffice. Microsoft has the power to negotiate the amount of money it gets from each sale of Office, because retailers can't just refuse to sell it. It's just not a regular app. It's the most widely used and bought app in the world.
Given the economic power of both companies, Apple and Microsoft could negotiate a different percentage instead of 30%, or Apple could even give away the 30% fee in order to have Microsoft Office at the App Store. If Apple doesn't do that, users of iPads and iPhones may well live without the highly-desired Office.
It's the way the world works. Everyone needs to eat, and writing the software is no more or less important than any other portion of the chain to get it running in your environment.
Karl P
Yes, and that applies to small developers. They must eat and then they must submit to Apple's wishes. But Microsoft doesn't have to. Microsoft can live without iOS.