Doing that would probably create a fairly popular blog post with followups. It might even get to the reddits and hackernewses and generate tons of comments where people would duke it out on issues on user choice vs the safety provided by a curated walled garden. There would be hundreds, if not thousands, of snarky tweets that make their poster feel superior for a while but are ultimately not productive. To quote Star Trek Deep Space Nine:
Spare me please-think-of-the-children speech and I'll spare you the users-must-have-control-over-their-own-devices speech [1].Having us, the user and developer community, argue about this issue is pointless, unproductive and actively harmful. This particular phenomenon is not new, it even has a name. In fact this approach is so old that the name is in latin: Divide et impera. Divide and conquer. All the time and energy that we spend on arguing this issue among ourselves is time not spent on working towards a solution.
The actual solution to this issue is conceptually so simple it could be called trivial. The entire problem at hand is one that has been created by Apple. They are also the ones that can solve it. All they have to do is to add one new piece of functionality to iOS devices. Specifically that users who so choose, can change an option in the device they own allowing them to download, install and use any application binaries freely from the Internet. Enabling this functionality could be done, for example, in a similar way to how Android phones enable developer mode. Once implemented Apple would then make a public statement saying that this workflow is fully supported and that applications obtained in this way will, now and forevermore, have access to all the same APIs as official store apps do.
This is all it takes! Further, they could make it so that IT departments and concerned parents could disable this functionality on their employees' and children's devices so that they can only obtain apps via the app store. This gives both sets of users exactly what they want. Those who prefer living in a walled curated garden can do so. Those with the desire and willingness to venture outside the walls and take responsibility of their own actions can do so too and still get all the benefits of sandboxing and base platform security.
Apple could do this. Apple could have done this at launch. Apple could have done this at any time since. Apple has actively chosen not to do this. Keep this is mind if you ever end up arguing about this issue on the Internet. People who have different priorities and preferences are not "the enemy". If you get into the flaming and the shouting you have been divided. And you have been conquered.
[1] Might not be a word-for-word accurate transcription.