Owning both a gas and diesel at the present time, I can tell you the gas engine is much less expensive to maintain. The 1 ton diesel takes three times the oil for an oil change, more transmission fluid, more cooling...etc.
Because of this, it can be worked harder, and longer, without over heating.
I agree to a point with Joe, a half ton, especially a newer one, can tow a trailer but they do it under more strain than a larger vehicle.
I don't think the "pucker factor" is the same, and a somewhat larger truck offers a more stable ride, has less sway in the corners, has larger brakes, stops better, handles better when the load shifts, and is generally more comfortable to pull with especially at highway speeds.
Some will feel safe pulling with a half ton, others won't and that's the reason I think you'll find more 3/4 and 1 tons in the parking area.
If you're going to make a pull on a hundred degree day up a steep incline the half tons are at greater risk for heat related issues when under a heavy load for a prolonged period of time. I'm of the opinion, half tons are more suited for shorter duration trips, rather than long continuous use pulling a load.
Here in Chattanooga we have some significant hills, (not nearly like out west) and when pulling with the older 3/4 ton gas burner I always tried to plan my pull during the coolest time of the day as I can watch the temp gauge rise in warmer weather.
Face it, a super duty is called a super duty for a reason.