One could certainly make that case in terms of the historical quantity of published titles (though I suspect a more thorough examination would put the ratio closer to 3:1 or 5:1 rather than 20:1). But maybe not in terms of what gets purchased and, more to the point, played.
The strongest "data" point of anecdotal evidence, as far as I am concerned, is those adventures that enter into the zeitgeist of D&D.
There's a reason that Goodman Games' Dungeon Crawl Classics have the words, "No NPCs that aren't meant to be killed!" proudly displayed on the cover. It's funny because it's true.
And Goodman Games built an entire company on the back of the DCCs by tapping into the zeitgeist.
If there's an untapped market out there, somebody really ought to get on it and give Joseph some competition.
But it won't be me because I play beer-and-pretzels, hack-and-slash D&D.
I'm a Philistine, I know...
Consider the adventures that get talked about here on EN World.
Don't be silly. ENworld isn't representative of gamers at large!
Snark aside, let's be frank: We
are a different sort. We're all food critics, sitting around insisting that McDonalds must be failing because
nobody in our social circle eats fast food hamburgers.
Finally, when you cite WotC, don't forget that their adventures aren't "all dungeon, all the time" either. KotS was only 50% to 70% dungeon, with wilderness, town, and social encounters a big part of it.
But how much of "wilderness" counts when the "wilderness" encounters basically boil down to that? Encounters? I'm not seeing that as being significantly different than dungeon crawling just because it's outside.
If the encounter boils down to a tactical engagement where the object is to kill the enemy and loot the bodies-- regardless of where it happens-- I'd say you're playing to the strengths of the core game.
And let's not be dismissive of the dungeon format as if it is nothing but dozens of rooms strung together with absolutely no pretense for either the monsters or the PCs to be there. "Dungeon" simply does not equate to "No story and no interesting NPCs."
I note that Monte didn't launch his new venture with "Interesting-NPC-With-Whom-You-Can-Roleplay-a-Day."