wow - this is a great thread
while the adams and westons of the world are definitely the people that are remembered in the "books" and history of photography courses, i think the regular guy/gal with a camera is the one that makes the most impact.
i remember seeing one of those sunday morning shows maybe 10 years ago.
they did one of their segments on this old man who lived in a small village somewhere - midwest, smokey mountains? i don't remember exactly where.
anyhow, he documented his region, the people that lived nearby, you name it, he photographed it. they showed the glass plates, talked a little bit about his camera, and photography. the images were just beautiful. after seeing the photographs you got a sense of place - you saw people as they were, the the nick-nacks in their homes, you saw their land, the way they farmed, as well as the region that they lived --- a real social history.
i actually have a degree in "historic preservation" and rather than working in a historical commission, planning agency or environmental firm, i am recording regular people and the built / unbuilt environment around me. i find it to be more rewarding to a habs documentations or photograph streetscapes than working on big projects doing national register nominations &c. in 2, 50 or 100 years someone can go to the local library and look through the photography books of streetscapes or habs submission and actually learn something from them. it might be as mundane as what trash cans or traffic lights looked like, or it could show what buildings existed and the context that they existed or even an occupational thing like what a "record store" owner looked like. i don't know may people except for geneologists or preservationists that even know what a national register nomination looks like
maybe the adams and westons will be remembered in art books on television specials on pbs, or on posters, but in my book, the "regular guy" steals the show.