My understanding of how carjackers get into your car in the first place (in some instances) is that they use devices that I wont name here, to mimic the existing RFID from your already programmed keys. This allows them to get into the truck and start it because the vehicle thinks its one of the original keys sold with the vehicle. In other words, although what you are talking about is another security measure to deter theft, they don't always need to create another key to gain access. This is why something like IGLA is so valuable. If you don't have the correct password to start the vehicle, you just aren't taking it. End of story. Unless you have a flatbed of course. Then you're fucked.
