It seems to me that the architects & engineers of the early 20th century over-built for structural integrity. This is probably because so much of engineering back yonder was empirically based and had no rigorous theoretical support.

In the second-half of the 20th century physics and engineering made huge advances in theory. Also the materials sciences made tremendous advances. This has allowed architects & engineers too employ incredibly graceful designs that are usually much stronger than their over-built ancestors. These advances also allow designers to build closer to tolerances than ever vbefore. IMO there is NOTHING wrong with that. On the contrary it allows design and construction of structures barely dreamt of a half-century ago.

There is a downside, as there always is. In this case, building closer to tolerances, it puts greater emphasis on QA/QC from beginning to end. This is in contrast to the previous century when over-engineering and over-building aided in structural integrity even when QA/QC and post-construction safety inspections may have been less demanding.

To put it in engineering terms we are better acquainted with, I'll bet that the w123, w124, and w126 were probably Daimler's last largely empirically constructed cars. I'll bet the immediately following generations were more solidly grounded in engineering theory, allowing designers to push closer to tolerance limits than ever. This would mean that the subsequent cars would undoubtedly have more refined details and be more efficient in every way. The downside is that if anything screwed-up in the assembly QA/QC it would be far more likely to result in problems later as compared to older design models.

Uh, ... I'm guessing. Not an engineer.

B