I think part of the problem is that after 100+ years of increasingly industrialized bread, most people today have rarely if ever encountered "real" bread (including bread that is actually 100% whole-grain). I can't find a citation at the moment, but I've heard from multiple sources that in the US, commercial bread only needs to contain 51% whole wheat to be able to be marketed as "whole wheat". So in reality when you see "100% Whole Wheat" on the shelf, most times it's really more like a blend of white and whole wheat (plus a whole bunch of other preservatives and other junk). If you actually bake a loaf at home with only whole-wheat flour you will get something that is much darker and denser.
There has been a similar phenomenon with "rye" bread in the US. Most bread labeled "rye" that you see on store shelves here is a variant of a deli-style bread originating in NYC. It is mostly white wheat flour with a little bit of rye flour and caraway seed added. The flavor people associate with "rye" bread is really just the flavor of caraway seed. In contrast, true whole-grain rye bread is a very dense old-world style bread that you almost never see anymore except for maybe in very niche artisan bakeries. Example: https://i.redd.it/bhwihp6j7dr01.jpg