Hm, German aircraft came with a stressed skin construction, which was proven to be both lighter and more damage resistant than some steel tube framework. Additionally, the German safety factor of 1.4 is against plastic deformation, not against failure. So while you might see a German aircraft bending a spar at 1.7 times the load, it won't have parts fly off or disintegrate.
The same stressed skin approach was used on the wings, at least that of the 190. It used stressed skin in place of a strong wing spar - retaining strength, increasing damage resistance, at a lower weight. If you don't know that, you'll just look at the puny spars and think it's weak.
And WRT damage, plywood sucks in comparison to aluminium.
Imho, Han oversimplifies here, might even be wrong.
Maybe if there was a confusion (language barrier and such) it might be good to bring those sources you talk about. Your 1.4 / 1.7 example could be a point that needs to be checked again.