Depending on the option package of your truck. That could be for heated seats, power seats, ejector seat.......
Most of the time when a car maker does a production run for a common item, such as a wiring harness for example. They will design it for the option packages the truck/suv/car CAN have. So when it hits the last leg of the line, when all the bells and whistles get added, it's plug and play.
Any options not purchased? They will likely leave the plugs and connectors secure, but nothing plugged into them. Consider it this way, how many different harnesses would they need if they made an indie one for each option package sold? It's just easier to use a universal harness for that year and model...and add the goodies as needed.
S-