AnFI
You quote the great Kelly Johnson but you fail to comprehend aviation design.
Kiss does apply in the basics, but after that one has to go on to consider safety issues.
And another Great, Charles Lindberg, chose to fly the Atlantic with only one engine, based on an early instance of FMEA reasoning.
It is the logic and math behind each and every FMEA that determines the level of air machine complexity. No argument, not even that of good engineering practice, is permitted to prevail.
FMEAs, oh how I hate them. Once you have one on your CV, every employer from whichever hemisphere, gives you another, another, and yet another of these brain-splitting tasks. Oh, the computer will do it all for you. Oh, no it won't! The final arithmetic is the easy bit, it is the up-front design failure mode analysis that hurts.
Please, by all means, go out and fly your airborne chariots about God's good sky, but argue not about design issues.
Thank you,
henry_crun