In engineering we don't have a continuous flow of incrementally better designs coming out over time. We go through periods of relatively stable design concepts, and then there is a brief period where everything fundamentally changes. This principle of design innovation is best illustrated by bridge building technology.
There have been a succession of bridge types; timber, masonry, wrought iron, steel, truss, prestressed concrete, suspension, cable stay, etc. Each successive type took advantage of both design breakthroughs, and advances in materials to span ever increasing distances with higher and higher loads. In each case the state of the art was slowly advanced until there were a few near misses and then a notable catastrophe or two when things got pushed a little too far. That triggered the next wave of innovation to occur, and the old methods were left to history It's almost as if mankind needs to exceed the limits of what we know how to do, before we even want to consider taking on the next round of big improvements.
For example, we really weren't much interested in jet engines during WW2 until compressibility effects above Mach 0.75 put an end to the piston engine's ability to go any further.
When you think about how we train young engineers with the experience of older engineers, and the human nature of wanting to minimize risk, it's not surprising that we make these kind of advancements in big leaps by visionaries (when the timing is right for them to finally be heard) rather than by steady progress within the engineering fraternity.