You can easily have a device with disabled root access and a curated store as a default and make gaining root access an added functionality (similarly how Android Nexus phones require you to issue a fastboot oem unlock command).
Where does this idea that the only alternative to not having some non-technical people install malware is to forbid root access to EVERYONE else?!
i installed linux when i was 12. i've been working in this field for nearly 20 years. i'm abnormal, as 'techie' as they come, and i really just don't give a shit about having root access on my iphone. in fact i pretty much use it for a handful of things, primarily messaging, and that's it. i view my phone as a fancy microwave oven.
from a business point of view, you might as well ask amazon for root access on their hypervisors, or network switches. some people give you that. others don't, because they just care about the people who want that.
How do you know?! There are billions of people out there not using Apple devices, how do you just claim that the demographic is vanishingly small? How did you measure it? Apple doesn't even own half of the market.
Some minimal level of responsibility of action from a users side isn't unreasonable. Being locked out from your own hardware because there are a few uneducated users out there is absurd.
Not to mention that now there are actually viruses and exploits out there that install themselves through security holes on users devices and the users can't remove them because they're locked out!
If you got an older iPhone, it's best not to open random PDFs anymore.
I was kind of thinking more of examples of malware where people were actually using the lockdown of the OS to stop users removing it, but hey I said exploits and that's an exploit.
I think CyanogenMods solution, where root access has to be enabled in the Developer Settings, which have to be enabled by tapping the Android version number 6 times, is the perfect solution: My mum would stop immediately doing such a complicated thing if she wanted to install something.
That seems to me to illustrate the point of a locked down environment fairly well...
As a result, there will be more malware if you even make enabling root access an option. It isn't surprising that Apple and others are happy just not catering to that small segment of the market.
This is largely solved, I think, by the current system. People who know/want/understand the risks, can have a rooted phone. But it is not trivial for the average layperson.