That's because they considered AI a nearly solved problem, so the brightest minds stopped working on it. I can't find a reference to that statement, but I recall reading it from someone credible.
Complete nonsense. I've worked for the Pentagon since the middle 80's, it was and still is by far the biggest consumer of AI. The brightest minds of the 80's just couldn't deliver a working AI system, despite the government investing billions in LISP and Ada projects.
The same happened in Japan and Europe, their best CS people failed to deliver the promised Prolog AIs.
