Not that these types of apps are good but Apple should allow people to void their warranties and sideload open source apps like you can easily do on Android phones.
I think apple is paranoid about their battery life claims. By not allowing sideloading non-approved apps they have more control over this. Especially with their claims of "x hours of web browsing" and "x hours of video playback"
Apple isn't "paranoid about their battery life claims", they are paranoid about losing their taxation funnel. Everything else is contrived apologia in defense of their app distribution monopoly.
They wouldn't want even the appearance of it being an Apple product running crap on it. If there was some way to completely distance themselves from it, maybe, but pretty much a non-starter.