I feel it’s only “controversial” insofar that the developers have a financial vested interest in seeing this percentage be reduced all the way to zero percent so they can keep more of that money for themselves. In this context, I don’t think they are going to be open to any sort of justification which would led to them having to fork out one cent more than they absolutely need to, since it is not in their financial interests.
Finally, the truth of the matter is that the iOS App Store is Apple’s intellectual property. They could charge developers 50% if they wanted. I maintain that I do not find 30% unreasonable so long as other companies such as Steam, Sony and Nintendo continue to do the same. If you want to argue that these companies re-invest their profits into supporting the game market (whatever that means), I can also argue that Apple has helped do its part by aggregating the best customers in the world, and creating a trusted App Store that has conditioned users to trust the download process and buy more apps than they normally would have.
Would you rather have 70% of a larger slice of the pie or 100% of a smaller one? That, I feel, has been Apple’s value add. They grew the overall pie for developers by making it safe and convenient to purchase apps. But it seems that over time, developers either forgot about this, or have simply come to take it for granted, or maybe they just want their cake and eat it too.
Like I said, we can argue until the cows come home about what a reasonable percentage cut is. Epic isn’t a good yardstick either. At 12%, their store still isn’t profitable, and continues to lack basic functionality. it’s just not very well run overall, and the only takeaway here is that it’s easier to charge less when you are also doing less for that money.
It’s a huge leap to go from “Apple does not deserve 30%” to “Apple does not deserve a single cent for their efforts in maintaining the App Store”.