It’s definitely an interesting topic, however technically it’s not as easy as it seems.
One thing is what you mentioned, App store is quite strict, to it would need to be investigated how these plugins could be distributed.
On the app’s side, it’s also a significant amount of work to make it more modular, to be able to effectively work with these kind of add-ons / plugins.
It’s not out of question, but something that we are not actively working on right now.