Hiya.
It sounds to me that you're looking for setting books, not adventures. That's exactly what a setting is - a backdrop for adventures with no included story.
That's what a setting book
should be...take a look at the Greyhawk Folio or even the Greyhawk "gold-edged" box set. To me, thats a perfect campaign setting.
For an "adventure", I'll use my fave of all time...Keep on the Borderlands. I've ran no less than three, full-length (2 to 4 years each) campaigns using that one, simple, 32 page booklet. Each of those campaigns were quite different from the others. In one, the evil clerics were the focus, with a lot of political intrigue and whatnot going on in the actual Keep, secret deals struck with various denizens of the Caves, etc. Another had the lizardmen as a focus; the caves were originally where they were from (I added water here and there and made the main box canyon that the caves are in more swamp-land like). The lizardmen had been "kicked out" by an onrush of other denizens who were in turn fleeing from some nasty, organized giants who lived in the mountains to the NE. The giants were lead by a charismatic leader, and semi-secretly getting ready to assault the keep because of some giantish relic that was supposed to be there, buried under the Black Tower. Lastly, I had a campaign revolve around the mad hermit and how he became mad; I added a dungeon complex between the 'caved in tunnel' in Cave K (IIRC) and the "Unknown Cave" on the wilderness map. That dungeon was made by a planar-hopping wizard named Mogg (a recurring NPC in many of my fantasy games...not just D&D). The hermit had gotten caught up in Mogg's planar hopping and it drove him mad, spending about a century in a pocket dimension where he didn't age, eat, drink, or sleep...but the hermit held a secret to a trap/trick in the Dungeons of Mogg (Cave of the Unknown).
Anyway, the point is, I had very little to "rewrite" for all three of those campaigns. I could just add on or ignore little bits as needed. No muss, no fuss. No NPC was rendered "useless", there weren't paragraphs (or pages) wasted on "story background" I was never going to use, etc. For me, that's the best form of adventure module; one that lets me add what I want and
easily ignore the hints/suggestions tossed in throughout it. As I said...coming up with story and NPC motivation is the easy part; it's drawing 6 levels of dungeons, ruins and other maps, filling them with traps, treasure and monsters, and designing a few random tables (wandering monsters, weather for the area, rumors, etc.). That's the stuff that sucks up time, not the story/plot stuff. Hell, sometimes you don't even need to start with a story/plot...the players will start to imagine all sorts of neferious things going on, and as a DM it's your job to pick up on that. Run with it. Improv the stuff that they seem to really be keen on. If you have enough maps, encounters, rumors, etc, then it's really easy to ad-lib. DM'ing becomes a fun and creative experience...as opposed to simply being a "task delegated to one player, who runs the monsters and follows the plot/story". I got into RPG'ing for the creativity. I didn't get into it to follow a script.
^_^
Paul L. Ming