I can't follow your order of thoughts and conclusions on your first paragraph...
What I mean by that is that you can be influential in the history of photography, and yet still be overrated as a photographer. Ansel Adams falls into this category in my opinion, simply because he was influential as a printer and the Zone System had an impact on large format photography, while his photographs are not particularly outstanding.
HCB falls in a similar category in my book. The actual invention of his style had taken place a decade earlier:
This is "Three boys at Lake Tanganyika", shot by Munkácsi in 1929, and cited by HCB as the only picture that ever influenced him.
So in my opinion, HCB's legacy is mainly in founding an influential agency and coining a powerful label for a style of street photography he was practising, but not in being a great innovator of photography.
Whenever I went to HCB shows, they have left me slightly bored. I can sympathise with what Roger mentioned earlier, that there are some photographers where it is better to look at individual shots rather than the whole œuvre. He mentioned Rodchenko, and I completely agree; I adore some of the man's shots and much of his graphic work, but if I want to see that, I'd rather look through 1920s and 1930s issues of "USSR In Construction" than through a Rodchenko book. And HCB, at least in my opinion, is such a case as well.
And about Cartier-Bresson, his fame and how he is loved, has no relation with the brand he used... Leicas were just the great option then: first he used Barnacks and then Ms...
Well firstly I don't care much about what gear he used; he could have used a Contax or whatever, but in his case I think it makes no difference at all.
And your assertion that how he is loved has no relation with the brand (or rather the camera type) he used - I don't think I agree with that. Every second discussion about the "rangefinder style" or the "Leica style" of photography etc. is guaranteed to mention HCB at some point. We have a forum full of rangefinder enthusiasts here, who see the rangefinder as the primary means of distinguishing themselves from the rest of the photographer crowd. A lot of people here try to imitate a style of black-and-white, decisive-moment-seeking street photography that they associate with HCB, simply because, to them, this is how rangefinder photography is done and what it should accomplish. You have evidence for that in discussions all over RFF (and other places); there are even street photography contests where you can win a rangefinder by producing this kind of shot. So I think it's not an unreasonable assumption that people in a rangefinder forum are likely to love HCB more.