Ask why we’re still so dependent on F-15s. The Tornado and F-15 both were developed in the early 1970s.
Hell, ask why we still depend on the B-52. . . .the NEWEST ones are over 50 years old. . .
In many ways the "Flying Fin", the B-52, the KC-135 and the C-130 are testaments to the old school slide rule designers. Man, they built 'em to last.