It really happened gradually, though, and with much less surrounding complexity. To give an analogy, OSes developed really fast, but any significant change in the kernel now will require lots of caution and scrutiny.
Also huge advances can have lots of things not "solved" - the first vehicles sucked majorly and were finicky as all get out, but compared to a horse-drawn cart they were so amazing as to excuse all the failings.
Modern cars are so good that any advancement is going to be incremental, and so it will take longer.
