I don't think drum brakes all the way around are that bad. Many of the older vehicles don't weigh what today's vehicles weigh and don't need a fancy brake system - just a safe one. Square inches of shoes to drums will work great, if they work. To work their best, dual master cylinders are, as you say, one of the safer ideas to come out of Detroit in the years since many of our trucks have been built. With a dual master cylinder, it has to be a major, major problem if you can't stop.
It's fine to get going down the road straight and fast, but you gotta be able to stop them, too!
Joe
