I think there needs to be a distinction made here. People buy a truck to be able to do work...tow, haul, etc, but that doesn't mean the primary usage of the vehicle is to do those things. When I'm driving to or from work (in a city) and see half ton pickup trucks in the normal commute traffic one right after the other, that says a large percentage of them are people with 9 to 5 jobs that are using their truck as a commuter vehicle. Those same folks use the truck to pull their boat/motorcycle/camper etc on weekends, for vacations, etc. Only a few are obviously being used as part of the actual work the owner/driver does.
On the flip side, when I see 3/4 ton and 1 ton trucks the majority are being used as work trucks in some fashion....marked utility vehicles, marked commercial vehicles, towing trailers, etc. You don't see too many people buying 3/4 ton or larger trucks and using them as their daily commuter (although it does happen). I know a number of folks who own 3/4 or 1 ton trucks, but they usually stay parked except when they're actually towing their trailer/boat/etc.
It would seem that many/most people buying 1/2 ton trucks use them as daily drivers, and that isn't the case nearly as often with 3/4 and 1 ton trucks. So sure, they buy 1/2 ton trucks to be able to do work, but that's a secondary function for most of them.