Very interesting read, start to finish!
Personally, I'm a very big fan of his playing. Always have been no matter the guitar. I've also seen him in concert, up close (front row center), and came away very impressed by his performance, especially the Bach. I do agree though that certain types of music or periods (like Baroque) suit his sound better than others. I think the earlier the material, the better he comes through, generally speaking. It's hard to find any faults with his Bach and Scarlatti for example, whereas he doesn't quite invest himself enough emotionally in relatively more modern music such as the Villa-Lobos Preludes, which I have been paying attention to lately. When I listen to Manuel Barrueco play the Preludes, or Julian Bream, and then switch back to Williams for comparison, the difference in "warmth", for lack of a better word, becomes more evident. On the other hand, he did acquit himself quite well with South American rhythms in the El Diablo Suite selections he recorded a few years ago. Maybe he just simply prefers certain styles, or composers, over others.
Nevertheless, he has rightfully earned his reputation as one of the best who has ever played the guitar. No doubt about that. And as he ages, so do we. Our own ears and sensibilities undergo changes that likely impact any current views and opinions we may hold on topics dear to our hearts, particularly when those initial memories and perceptions were formed so many years ago.
Lastly, just a comment on Scarlatti recordings. Although he is better known as a composer, my very favorite recording of Scarlatti sonatas is by Leo Brouwer. He may not have the technical chops of a JW, but he more than makes up for it with his impeccable phrasing and good dose of "warmth". His musicality really shines in this effort. Well worth a listen!
Thanks for this very enjoyable thread.