I'm all for shipping the necessary cables with hardware items, but the fact is that this isn't the way it works, like it or not. Printers and similar devices really have no excuse, because you absolutely need that cable, and there is only one kind of cable you can use, however they have their reasons. One example I can think of off the top of my head is the new printer I just bought. Since I'm selling my old printer, I am simply using the USB cable from the old printer for my new printer, and a new USB cable is not necessary. In this case, it would be a waste for the printer company to include the cable with the printer, as I would never use it.
I also understand this philosophy more in the case of the iPod. The USB cable is NOT required for an iPod, and many users will use the included firewire cable. So in the iPod's case, the USB cable isn't necessary, and may not even be used by all users, so in a way, it's a waste of money for Apple to include these cables with the iPod when they may never be used! And who knows, for the less-intelligent users out there they might cause more confusion than anything!