Regardless of how much value it provides, we have no choice if we want to sell on the platform. In a hypothetical world where we could either sell ourselves or go through Apple, if it really provided that much value, everyone would still go through Apple. I kind of doubt that would be the case.

The distasteful part is where they disallow you from using a different payment processor.

Well it would be nice if you could buy IAP from some other well-known merchants (for example, if you could pay MLB.tv directly to subscribe from the app rather than buying a subscription by paying Apple), but imagine the UX if every single app used their own store and you had to enter your card number for every different app, and all of the people demanding refunds from Apple when Apple had nothing to do with the purchase. Imagine how many people would give their credit card to an app thinking it was Apple they were trusting, then their card gets stolen.

It might be distasteful, but it makes sense from a risk avoidance standpoint

I agree there are some costs, but I think that the amount Apple feels entitled to take is still distasteful. As there is no competition, the pricing is quite high.

That "no competition" stance requires defining that Apple has a monopoly on selling their own products, which is true, but fairly useless. In the larger market in which iOS is a participant, they have quite a competitor in Google, with a number of also-rans clawing for attention.