$99 per year for your developer account required to distribute applications. At AWS pricing, that's a bit over a TB of traffic. At any normal pricing, that's anywhere from 10TB to a few hundreds. At volume pricing, that's even more. How many apps are paying for traffic they don't use? Apple pockets millions.
I also don't think Apple should be coerced to host content. However, as long as they insist on gatekeeping all installs on the iPhone platform they should be. If Apple doesn't want that coercion, they are free to relinquish their app store monopoly.
I definitely think they should be coerced to host content if they insist on being the only avenue of getting content out on the platform.
If they don't want that burden, which is very understandable, then maybe they shouldn't be the sole God gatekeeper of content? That's a choice, after all, and one they willingly made.