I fully recognize that if I am in an accident at speed in the truck, I am 95% likely dead no matter what kind of seatbelt it does or does not have.
That said, I feel more comfortable wearing one because it is what I am used to. Other people in my family are much more hard-over on their necessity and it is easier to install them than argue over it.
If the front end does not completely cave in, a shoulder belt will help with not putting the steering column through my sternum. Which is a bonus.