I'm not after blazing acceleration or fantastic mpg. With fuel prices being what they are I cannot justify spending money to go backwards. I've had diesels of one kind or another- commercial boats, big rigs,2 strokes etc. . Usually economy improved with each new purchase until the last 15 years or so- particularly in over-the-road vehicles. As an aside I notice all the UPS delivery trucks in my area are now gas.
I can't disagree with your logic. When you analyze the purchase decision from a practical point of view as you are it's pretty hard to justify a new one. An old 12 valve with several hundred thousand miles on the odometer and a modified injection pump will do anything my '08 or another member's 2012 will do.
I paid cash for my '08 and it does everything I want it to do in comfort. With 115k on the odometer and good maintenance it will last me as long as I want to pull my trailer or own a truck. I doubt I'll ever purchase another one.