I have an unfair bias because I design PCBs as a significant part of my job, and switching out to USB on this board appears to be a non-issue.

I have a Pico in front of me, and there's plenty of room there for a USB-C footprint and the two 5.1k resistors. Given that, I cannot reasonably agree that the "design" stage is significant.

In other words, it's a change that I would make to my own board in 2-5 minutes because the stakes are low. My ballpark guess is that such a change at RPi would have to go through a proposal stage, a PCB change review, and then there would be dozens of places to update documentation.

Since backwards compatibility is non-optional, this would result in a separate SKU, which means that the whole distribution chain needs to be updated with a new product.

So, I acknowledge that when you're working at their scale any change like this is the definition of non-trivial. What I don't agree with is the conclusion that it's not still clearly the right thing to do.