Storm Raven, the deal with dungeons is just what Gygax, et al., related -- and what I and other DMs know from experience. Another bit is that TSR in those days went in for publishing (sometimes expanded or reworked) tournament scenarios as a way to get more return on investment. Maybe Frank Mentzer or Tim Kask would give more answers to your questions -- or, concerning later decisions, people who were involved in making them.
You seem to come at the artifacts (modules and books) from a perspective isolated from the context (introduction via play, reading The Dragon, going to club meets, attending conventions, etc.) that informed practically every D&Der I met 25-30 years ago. Things that from inside that context amount simply and concretely to the way things were when we were there seem doubtful and merely theoretical to you.
That's a pretty frustrating phenomenon with which to deal; fortunately, the heyday of D&D is not among the more serious affairs of 20th-century history!
