The models without the touchbar have fewer USB ports. That’s why it’s questionably optional. My work setup uses two external monitors and wired Ethernet. So I’d like three ports and no touch bar. If I want enough ports for my setup, I have to take the touch bar too. I don’t like having to make that kind of choice.
I think they used fewer or smaller usb controllers in the cheaper model. So it only has bandwidth to drive two ports. And I suspect it was intentional to encourage high end users to take the one with the touch bar, as a way of driving adoption.
