I believe D&D is, at its heart, a light game of explore and conquer.
Its core popularity and general market stability are founded in dungeon clearing, treasure scooping and level advancing. A lot of people who play infrequently, and virtually all younger players, play this way. They don't get hung up on things like character development. Or, rather, things like finding a +2 sword or gaining the ability to toss EMPOWERED fireballs ARE character development.
I bet there are more people who view it that way than as a deep plot development experience. (or even shallow plot development
)
But those people are far underrepresented at ENWorld. For obvious reasons. Didn't we determine some time back that regular posters here are somthing like 50% DMs? I know that none of my players post here.
Certainly we spend more per person than the lighter players do. But they still represent a core support. If they were not there, we would notice the repercussions.
So the rules of the game maintain SOME bias towards dungeon crawls. One segment prefers that and the other segment wants it in as part of the overall mix. So it gets more than an equal share.
Obviously the core rules provide for MUCH more than just this. I don't think it would be accurate to call it truly a Dungeon Crawling game or an all-enclusive world experience game. It is an all enclusive game, with a clear bias towards dungeons.
So my answer to the question in the first post is "focused far more on dungeons".
But remember, you will find a fair number of statistical aberrations in this poll, but the target audience is composed of statistical aberrations. (Though I'd guess its around 1/3+ of gamers, so aberration may not be the best word.)
Besides, those of us who prefer more variety tend to be much more comfortable, not to mention inclined, to house-rule or otherwise tweak things. Which is good for the industry because it makes this minor problem largely self-correcting.