in answer to the question, i feel one reason why adams has become such a monumental figure in popular culture is the fact that his subject matter appeals to a wide range of people, across all political, cultural, and socioeconomic strata. both artists and people with no particular interest in the artistic world enjoy his prints. it is, shall we say, a rather "safe" and ubiquitous subject matter. adam's lanscape photography simply has a wider appeal than the work of, say, man ray or ralph gibson. his acendancy over other landscape photographers can partially be explained through his undeniable technical proficiency.
however, another reason for adam's eminance is the fact that he, along with the other f/64 folks and allied critics & art historians, were on the winning side of the battle to define "fine art photography". they simply destryed the reputations of the competition, may fine technicians and visionaries among them. others here have mentioned mortensen, and i feel this example illustrates that, while adams may have been a brilliant technician, he was a rather loathsome human being. adams actively sought to destroy mortensen's career because it didnt conform to the f/64 definition of fine art, and after he succeeded in destroying mortensen's career, he even had the indecency to joke about his artistic demise. "artists" with such a small-minded and fascist mentality as this should not be idolized, unless you want others force-feeding their definitions of art to you.