Looking from the OEM's perspective, if they didn't need to add the Maxim part to BOM, it gives them a better profit margin. If the OEM manufactures 1,000,000 USB devices, that could result in a extra profit of $760, (Based on the back of envelope calculations).

Edit: Corrected the maths, thanks Syi.

One should make it clear that the quoted price on the Maxim product page is $0,76 @ 1000, so if you order 1000, you pay 76cent per chip. But you can easily find offers going down to about 50 cent.

https://octopart.com/search?q=DS2401%2B

As the DS2401 uses the 1wire bus, which requires a relatively complicated logic inside the chip handling device isolation and power recovery from the data line, it's not the cheapest option. Maxim, for example, has a SPI connected digital serialnumber chip going down to 35 cents.

https://octopart.com/search?q=25AA02UID

These chips all come in small SOT sized packages, if you really want to shave off the last cent the companies will be happy to sell you the bare dice you glue on your PCB, bond with wires directly to the board and protect with a glob of epoxy. Also: if you are going to build 1 million devices you'll not pay the standard list-prices but your procurement department will negotiate with high-volume sellers or the chip manufacturers directly. So, you'd probably pay around half.

But then.... if you are going to build 1 million devices you really want to have individually numbered, you might not use the off-the-shelf USB controller without serial number plus a 20cent serial-number chip, no, you'll redesign to use a 5cent more expensive usb-controller with unique serial number, and leave out the external serial-number chip completely.

You've added a few too many 0's to that, the savings for 1,000,000 USB devices would only be $760 which would definitely be worth it for customer satisfaction.

You are right! I think I will blame it on Friday-itis.

I really have no idea -- but I imagine the cost of adding a component/chip (any chip) would be higher than the price of the chip itself.

Layout changes, testing, assembly (even if automated) etc?