Actually the materials have changed much more than the construction methods. Which is why some cynics state that today we build aircraft from black aluminum.
Uhhh how many ' ALL black aluminum " aircraft are flying since the707 -321 you referenced? ( hint count 20 B-2 bombers plus current number of 787 ) compare to ' aluminum" aircraft flying or in production since 707.
As to your comments as to taking wing test to failure being under debate for some time - please notify BA and Airbus that they obviously do not understand the risks, nor do the agencies involved, and provide a list of those aircraft that passed the ' no failure ' requirements bnut which lost wings in service absent a bomb or similar and crashed. To prove your point you need not lilst over 100 such.
And at what altitude do you claim the temperature is significantlty hotter than near sea level absent speeds over mach 1 for commercial aircraft.
SR71- is/was not black aluminum - it was predominately titanium ...