The F450 pickup GVWR is capped at 14K lbs to prevent that insurance surcharge. Once you get into the chassis cab Class 4 trucks, you will see they have a 16.5k lb GVWR. Many insurance companies don't even mind that if you install a fifth wheel hitch or pickup bed, but they rate the liability highest with a flat bed style deck.
The F450 pickup only comes in upper trims with many options included as standard. You can buy a Class 4 or 5 chassis cab for less than this pickup. Comparing it to a 3500 from Ram or GM is not really fair - With its 19.5 wheels and larger Dana axles, it has a distinct advantage over the other pickups.