I get the appeal of placing written adventures/modules in an existing campaign world like FR or Greyhawk. And I understand that they can always be hacked to be plugged in to another setting. But is there (and perhaps we can ponder, will there be) adventures/modules created with a purely generic setting in mind? I mean, adventures created with no ties to any existing world but for the purpose of giving the DM the freedom to plug it into any world (or no world) at all. I could envision an adventure written in such a way as to leave things like the names of villages, towns, geographic locations, etc. Give it a tag (ie. Villiage A, etc) or leave a blank line in the actual adventure to be filled in by the DM. Something that can be easily tailored to each table.
If something like this exists already I admit my ignorance. It would just seem like a win/win situation for the most part. Purely generic modules can work for both a homebrewed world and for existing worlds.
First, that'd be incredibly limiting. It might work if the module was centered in a single location, but the moment you add travel, you start fleshing out the map. So if you had a single dungeon or a single town, it might work, but unless you aim for the vague "days travel" idea, you end up putting SOMETHING in there.
Second, how generic IS generic? Do we get named NPCs (Mayor Barlin, Aleena the Cleric), do we get named Villians? (Lareth, Bargle) what do we do about churches and cults? (The infamous Temple of Evil Chaos from the Keep, I'd wager). What about backstory? Why is there an ancient temple in the woods? Who is Lord Strahd and why did he invite me to his castle? A module isn't just a map and stat-blocks.
Third, What generic are we talking about? I guess we could say "Everything in the Holy Trilogy (PH/MM/DMG) is generic, except its not. A generic adventure where a red dragon and his orc minions attack a nearby village doesn't work in Dragonlance (no orcs), Ravenloft (no dragons), Planescape (unless its a village on Carceri), etc, etc. In fact, I wager that nearly any adventure you pitch wouldn't work on at least one published D&D setting, making "any setting" an impossible dream.
Now, I have said before that their might be a goodly market for ICONIC adventures (that is, adventures that hew very close to the cliche: a haunted castle, an orcish dungeon, a drow fortress, or a dragon's mountain lair) that doesn't fits the generic tropes of D&D, but still have some base assumptions about them. THAT I could see.
"Town A" adventures? that seems like a paint by numbers kit. I buy modules to have the heavy lifting done for me.