One of the biggest drawbacks of buying iOS devices is you can't leave. I swap everything out on my laptop and phones as needed, but on iOS you're stuck with Apple's app store, Apple's operating system, oftentimes Apple hardware, and there's nothing you can do about it. It simply ends up being so expensive.
And you generally have a shitty opinion of people and their ability to navigate technology.
As with most things, it's generally a cost benefit of convenience versus effort. Anyone can learn anything or transition to something else if they're willing to put the effort into it. It's just that most people aren't willing to put the effort into most technologies and that's their prerogative.
Do you regularly buy apps that cost hundreds of dollars? A vast majority of apps are within the $1-$5 range. We're talking about buying phones that are well into the high hundreds to thousands of dollars. That's a drop in the purchase and operating cost of the device.
They do a great job of integrating devices. As for the App Store, us in the EU will soon be allowed to install alternatives. I think the deadline is the end of March.