Why does Dodge go cheap with their steel?

I've got a 99 Dakota that is one of the rustiest things I've seen in a while. I got it 7 years ago and it was getting bad then, but truthfully I've nothing to stop the rust's march across the body. I will say, though, that at 180K+ it is one of the most reliable vehicles I've had. Always starts, everything works...it never lets me down. And that's after I dropped it through the ice and froze the block. Tires, brakes, alternator and water pump have been it for the last 70,000. Much nicer ride than my Ranger, too.