I think you hit on a few valid points. It does seem that while a relatively small minority, Brooks users are extremely loyal. They remind me a bit of bent riders in their enthusiasm for the product.

FWIW: On the "Great Myth" as you called it... I liked the only Brooks that I owned better before it broke in. It was OK but nothing special. After getting rained on for a few days I didn't like it at all. That was maybe 30 or more years ago though.

As far as why we hear so much about discomfort... Lots of things contribute to that including bike fit issues, lack of time spent riding, poor cycling atire, poor riding form, and in a few cases maybe even general wimpiness of the rider in question