That's true; a few cents of chip and a couple of cents more complex assembly, propagated through the supply chain. (there's a little bit of handshake for PD, billboard etc but I agree with your point that the cost will be pennies).

Once they become ubiquitous I imagine the usual forces will drive the cost way down so we'll end up with something like the current mix of good and crap cables. Hopefully nobody will advertise 100 W over 30 gauge wire, but probably...!