I agree that many photographers have been influenced by Adams concerning shadow detail. It doesn't help that Zone System testing only uses two points of density and that Adams' theory isn't the best. People tend to cling to what little information they have and with the Zone System, they don't have much. A more thorough understanding of exposure theory would have practically eliminated all the ZS testing zealotry that has arisen.
That's not to say that shadow detail isn't important in black and white work. Other photographic mediums have their own set of criteria. Psychophysical testing has shown that in general people find photographs with shadow detail to be the most pleasant. What is critical in such a test is the instructions given to the participants. The parameters for how they are to judge and offer their feedback greatly affects the results. In Jones' seminal work, print judges were given instructions to pick the image that produced in the viewer's mind what they best believed the subject looked like in real life. Basically they were asked to identify an approximate representation of the real world in black and white. Instructions such as these are aimed at what the average snapshot photographer would like to see from their vacation photos, which up until recently were the majority of film users. The instructions, as such, essentially excludes artistic interpretation from the judging parameters. In practice; however, I've found having the detail and not using it is better than not having detail in the shadows and wanting it.
BTW, shadow detail isn't about the density of the shadow but the contrast of the shadows, and minimum degree of contrast that most people find as acceptable is based on the overall film contrast. The importance of shadow detail / shadow contrast in the majority of black and white photographic use is why the black and white negative speed point is in the shadow area.