The iPhone would be unusable if it came installed with every possible app. Making apps opt-in gives users the power to decide which features they do/don't want. And apps are sold as limited tools for specific tasks, not as a rat's nest of do-everything features - like many desktop apps.

Apple could have split apps into different hardware categories, so instead of apps that used the camera you had Camera Apps as a separate category to Microphone apps. But that would have been exactly the wrong approach.

The Apple approach makes user benefits obvious and keeps the technology subservient to them, which is as it should be.

Although having said that, it's hard to imagine today's Apple making that choice and getting it right in the same ways.