Allowing side loading of apps would not impact usability in anyway.
Edit: It would massively increase the usability, allowing any apps to be installed, not just Apple approved apps, making the phone more usable to many people. Back in the day I had to buy a dev account just to load an emulator I wanted to use (it was open source) without rooting.
Edit: It would massively increase the usability, allowing any apps to be installed, not just Apple approved apps, making the phone more usable to many people. Back in the day I had to buy a dev account just to load an emulator I wanted to use (it was open source) without rooting.