>>tgsovl+Hz
It's easy. For the average user, device integrity is more valuable (by a lot) than side loading.
People that think this is unacceptable are not remotely average users. Average users benefit greatly from their pocket appliance not being a full fledged computer.
>>maxeri+8C
And people who are financially interested in letting users side-load apps (malicious or otherwise) are good at what they do. I mean, even Russian banks that are banned from the Apple App Store are still finding ways to distribute iPhone apps.