It's that people aren't exactly stretching their imaginations to picture their phone ecosystem going to hell. They've all been there before, and have vivid memories of what they don't want.
They are also not crazy to have different preferences for a phone and for a desktop. Just like you have different preferences when selecting a hotel room vs a house.
I don't mind personally I see the value they offer - they make products that are better overall for a large majority of consumers and their ecosystem just works for many use cases - it doesn't fit me particularly well but I see the value proposition.
Pretending that these store policies are driven by security is nonsense, those kinds of arguments tick me off.
Clearly Apple wants to make money. The only argument being made is that some customers choose the walled garden because they want a telephone, not a part-time job keeping the weeds at bay. As you say, that's (a component of) what they are selling, and they do it because it sells (long-term, in their estimation).
The phone ecosystem has already gone to hell, and Apple paved the way there.
Got any sources on iOS-specific, in-the-wild malware?
iOS certainly has malware and vulnerabilities, like any software, but they end up patched pretty quickly. It's definitely not the malware landscape we had on Windows 2000-2015 (arguably when Windows Defender got good).
And so your argument is that Microsoft should have forbidden anyone from using a different browser engine (like Apple does) to make things safer ? What if someone installed Chrome or Firefox - that could have leaks and then you would think less of the platform - right ?