What Colt said, These trucks were not built for highway efficiency, they were built to meet a military specification(milspec). In this case I think it had to be able to overcome a 18” curb at max weight? Weird things happen in the land of milspec, like the grossly oversized battery to meet a -40F CCA specification. That in itself wasnt the issue, only providing a 60/40, 12/24v dual volt alt to support such a large battery was the problem. The kind of problem class action lawsuits and recalls are made of in the real world, but perfectly acceptable in the land of milspec. Uncle sugar just whistles up a warehouse of new batts and alternators as needed
No you are not missing anything. It is just that these can deliver so much torque to the wheels that unless you are grossly overloaded, and trying to do something extreme like climb a 18“ curb, it would never all be used. You are dropping the 2:1 at the hubs, but for our typical use, you were never fully getting the 2:1 that the torque converter is capable of delivering out of the transmission. Minus the 2:1 at the hubs, the TC is stepping in and actually delivering some conversion(up to 2:1 as needed), so for our typical use, people are reporting same or better performance minus the 2:1 hubs.
For our typical use, dropping the engine back to peak torque at highway speed, removing the 10% gear losses at the hubs and bringing the driveshaft RPMs back inside the max RPM vs angle curve on the chart are all HIGHLY desirable changes from efficiency and safety standpoints…