The book is also so great because it highlights the creative aspect to programming - which they show could (also) be seen as an art form; where it's beyond the utilitarian aspects of coding; appreciating aesthetics / intellectual beauty. All for the sake of instilling in their students a more holistic understanding of the craft while doing so.
IMHO SICP feels "timeless" somewhat because of that.
I spent my life looking for such an elegant tome. If I had discovered it when I was 15 maybe my life would have been happier.
Utilitarian programming is like utilitarian food. Programming should be seen as an act of worship to the god of simplicity. If the artificial world intrudes and makes the program complicated, this is what leads to suffering. Ultimately it is the world which should be changed.
IMHO SICP feels "timeless" somewhat because of that.