The controller is built into the SoC. As is their standard practice for many years, non-Pro models receive the SoC from the previous generation of Pro models. Because this is the case, in fact they don’t have a choice other than spending billions of dollars to retool an older SoC.

The fact you and others seem not to understand this should be an indication you aren’t informed enough to have a valid opinion on the topic.

They'd have to produce a new SoC, which would be a lot of cost (and I believe generally a small power usage increase) for a feature that, to a first approximation, no-one would use. It is really, really uncommon to transfer large amounts of data over USB on an iPhone these days.