Bike frames are quite a good example of what I am wondering about. 20 years ago we were building the first of the real MTB ( off road) bikes out of steel, really supple and bendy, gave the really poor first generation suspension a bit of hand and the overall package was a quite supple but user friendly bike. I still have the bike 20 years on and still no sign of frame breakages or stress fractures.

Now I've since had two very stiff aluminium frames with pretty top class suspenders on, great bikes, but already I have broken both frames at the critical stress points.

My latest frame is built like a barn door weighs a ton but is considered to pretty bullit proof, and then I look at my skinny little lightweight bendy steel frame and think have we got things right here.