So what. Should my computing experience be crippled because people are ignorant to security practices? Should we hold the market back because uncle Marty keeps visiting gross sites with Internet Explorer?...
But it's not. You don't have to buy an iPhone. This isn't some bait and switch tactic. People who buy iPhones know the App Store is where they get software.
Apple wants everyday users to have a streamlined, simple, "just works" experience.
It is a common principle in many other facets of life. You can't just buy any prescription medicine for example, even though theoretically a well-prepared patient with access to the newest medical literature could figure out what he needs. But the vast majority most definitely cannot and relies on some kind of access-filter.
I would say the market even prefers the App Store model. Google/Android is working more towards the Apple model and not the other way around.
Devices that can’t (generally) run malware are a value, to some. I have computers, and I also have Pixelbooks and iPads. I use them for different things, and I store different data on them.
I will quote Benjamin Franklin
" Those Who Sacrifice Liberty For Security Deserve Neither."
https://boingboing.net/2012/01/10/lockdown.html
A few more relevant quotes:
"Freedom is not worth having if it does not include the freedom to make mistakes." -Gandhi
"Insecurity is freedom." -(various)