Devil's advocate: this is true. The people buying this icon pack, and the people who spend time on software customization in general, are a negligible subset of iPhone users. If you're making an app that aims for the lowest common denominator, options should be a low priority and well hidden once they're added.
If you're targeting a segment that likes options it's a different story.
I think this opinion is similar to the opinion that people don't value their privacy: it is a very convenient viewpoint to have when it comes to a company's bottom line.
Sure, if you approach the average person about an obscure topic like their privacy on the internet, they probably don't have strong opinions about it because that is outside of their wheelhouse, and they probably haven't given it much thought. If you couch privacy in terms that they are familiar with, such as drawing parallels to Supreme Court cases regarding surveillance and privacy, suddenly they care about whether or not they're being stalked online by corporations and governments.
For example, right to repair is something that most people don't think about. However, if you press the average person about whether they think they have the right to repair their own vehicle, suddenly everyone has strong opinions about it. People assume they have the right to use their hardware as they see fit, and aren't afraid of such options.
I spend a lot of time teaching non-technical people to use software, and in my experience the two things aren't the same at all. These sorts of users aren't too aware of the invasive aspects of modern programs, but if told, they're against it. However, they already know software with lots of options has those options. They just don't understand most of the choices and are afraid to try any in case one changes state in a way they can't get back from. More options scare and confuse them and make it much harder for these people (the vast majority) to use modern tech.
To be clear, I don't like the Apple approach. I think the options should still exist--but they need to be far removed from the UI without significant, non-discoverable steps.
I find weird that there's a whole market of plastic stuff with lots of colors and designs for the exterior of the phone, but somehow it's given that stuff inside the screen is different.
Maybe the subset of people who spend time on software customization is small because software customization tends to be low priority and well hidden?
An entire generation of developers is growing up being told that users like being told how to use their devices, and that options scare them.