Especially when there is a high end model specifically for people who are willing to bear the cost for higher end features?
Also note that it’s not just the module. They shipped cable would also need to be usb3. So they probably shaved $5-10 out of the BOM by using usb2 as part of an overall cost reduction effort which probably netted $20-100 in savings depending on far away this was from there target. In other words usb2 would have probably been anywhere from 5-50% of the target reduction they were seeking and even 5% would have been significant.
That being said, there may be strategic reasons why they’ve limited iPhones to 480mbps this whole time. The alternate framing is “iPhone 15 isn’t upgrading to usb3 alongside the usb-c connector migration”.
Apple hasn't officially announced it, but the cheapest iPhone 14 is $800. So it's extremely unlikely they will have an iPhone 15 for $500 or less.
Furthermore, all of this is notwithstanding the fact that the price of the iPhone is going to go up this year. So yes, you're getting less for more.