Kevin,
In my book, SS Blue is seriously underrated period. The 12-18 stretch is world class, and number 8 is a brilliant hole. The two “weakest” holes—10 and 11–are still very solid. So yes, I think BD is overrated relative to SS Blue. I also think the same about SS Red which has two great stretches of holes: 2-7 and 11-16. I am not a fan of 8-10 although I know many people here disagree with me especially about number 8. BD is a better course than SS Black. I thought that the routing of Black to be quite good especially the variety of holes, but the overwhelming bunkering and size of the greens (especially on the front) detracted from the overall quality.
Your questions strike me as on point although I am in the camp that rankings are subjective best serving for providing over drinks conversation and of course threads on here. And so as you note, BD is a very good course regardless of its place in the rankings.
Ira