Sorry if I came off as annoying.
To answer a few of your questions -
Yes, I do know what a V8 is, Yes, I do know what a wrench is and, Yes, my finger nails have been dirty.
I understand that the big bodied cars are typically more complex than the small ones for the reasons you sighted, and the costs to repair these items may add up. But if a car is designed for reliability, and not to fit a price point, then the probability of incurring these repairs can be lower, if the engineers do their job. I am an engineer, and know that through re-use, you can achieve the "numbers necessary to really perfect and reduce the cost". The W126 body style spanned 13 model years (1979-1991). While the body sizes and engines may have been different, there is quite a bit of re-use if many of the subsystems. The simplicity of many of these systems, and there modularity lead directly to lower repair costs. I purposely bought the last model year in order to maximize the likelyhood of a defect free car. So far, so good.
For the record, I have driven a "C" class. I test drove a 200 C280 and was so unimpressed, I went for the 1991 560SEL. I have also driven a 2001 E430 (brothers car). It is a very nice car, that he bought on my recommendation, but sorry, I don't have $50,000 to spend on a car.
If two cars rolled off the assembly line today, one was a 1991 W126, and the other was a 2002 W202/W203, which one would rate higher on the JD power survey?