Were you reading my mind yesterday Ken? that's creepy, sends shivers down my spine! I was at a (new) customer's office and they too insisted that a product code should be used as a primary key when we talked about the software concept. (They, that is, their DBA's) I told them nearly exactly the same as you tell here.
My rating for you.
Boudewijn Lutge®ink
The attitude of "An eye for an eye and a tooth for a tooth" will make this world toothless and blind (Gandhi)