I am not trying to be cunning or a smart Alec, but merely to highlight the financial side of the matter.
The iOS App Store takes money to maintain, and currently, money comes from the annual developer fee as well as 30% cut from app revenue. Apple does not take any money from free or ad-supported apps. I do not think that the iOS App Store should be a loss maker, much less expect Apple to fund it using iPhone money.
Apple has also made the effort to aggregate the best customers in the world (ie: users with more disposable income). I do not feel that it is unreasonable to charge developers a cut for the role Apple plays in growing the overall pie for everybody. What developers basically want is to be able to access and leverage Apple's user base for free, without giving anything back in return (the ability to sideload apps and circumvent the App Store would in theory mean that devs don't even need to pay Apple $100 a year).
If the ability to sideload apps was so important to users, the iPhone would never have enjoyed the success it does today. I feel that positioning the iOS App Store as the sole way of access apps remains the greatest good for the greatest number of users. For the fewer who desire more flexibility, well, there's always Android.
This helps ensure that users continue to have a meaningful choice of two sufficiently-differentiated platforms (iOS vs Android), rather than force one to become a carbon-copy of the other in the name of "choice".