Dwarves don't sell novels

[Hussar]

Besides, the non-standard setting of Isle of Dread was not the only thing that distinguished this module. It was also, for example, the first to take place mostly outdoors, not in a dungeon. And it was sold as part of the Expert Set so would have been one that many gamers would have played just because they had it. So you can't safely say that the popularity of Isle of Dread is attributable to its lack of traditional fantasy. There may be other reasons.

While that may be true, you are still missing the main point which you yourself brought up. The creators of D&D put Isle of Dread in the box set for the Expert Rules. They didn't include a "stock" fantasy module with this hugely popular hobby that was in its infancy. They chucked standard fantasy straight out the window and included a module which had nothing to do with standard fantasy. And it was popular.

It's so popular that Paizo is resurecting it for the new Adventure Path. The other two AP's have hardly been stock fantasy as well. But, the fact that the most popular adventure series in years is now steering directly away from stock fantasy settings should tell you something.

Thirty (ish) years ago, Moldvay and co. decided that D&D should not be limited to dead authors. To say that WOTC is suddenly doing something different ignores the history of the game. There are module after module that are not stock fantasy, as well as modules that are. The non-stock fantasy modules have generally been very well received and are among the most enduring of the modules produced.

Honestly, the centaurs would be cool. The others not so much. Then again, we could go back to fat halflings that stay at home and smoke pipes. That's exciting isn't it?

Edit for later thought.

Looking at the list in Dungeon 116, the top 16 modules are:

.5(damn, I numbered wrong) GDQ1-7: Queen of the Spiders: Compiling the giants G series, the drow D series, and Queen of the Demonweb Pits
1 I6: Ravenloft
2 S1: Tomb of Horrors
3 T1-4: The Temple of Elemental Evil
4 S3: Expedition to the Barrier Peaks
5 I3-5: The Desert of Desolation
6 B2: The Keep on the Borderlands
7 Return to the Temple of Elemental Evil
8 S2: White Plume Mountain
9 Return to the Tomb of Horrors
10 The Gates of Firestorm Peak
11 The Forge of Fury
12 I1: Dwellers of the Forbidden City
13 Planescape: Dead Gods
14 X2: Castle Amber
15 X1: The Isle of Dread

Now, of those 16 modules and series, we see how many that are not stock fantasy? GDQ has a giant mechanical spider among other things, I6 is horror, S1 definitly not stock fantasy, S3 had robots and lazers, I3-5 was set way outside standard fantasy, S2 definitely not stock fantasy, Planescapeead Gods about as far from stock fantasy as you can get, X2 had dog men with French accents and then X1 is again about as far from stock fantasy as you can get.

9 of the top 16 are outside what you consider fantasy. Over half. From all periods of the game. The idea that D&D was ever about genre emulation is silly.

 

[Turjan]

One of the classics of D&D gets a new interpretation, too. Including the spaceship .

Check here!

 

[Infernal Teddy]

No, you're the one who is mistaken.

Agreed. I just reread some of the stuff - I tend to work with older versions of most Märchen, so I slip sometimes...

 

[Kishin]

Now, of those 16 modules and series, we see how many that are not stock fantasy? GDQ has a giant mechanical spider among other things, I6 is horror, S1 definitly not stock fantasy, S3 had robots and lazers, I3-5 was set way outside standard fantasy, S2 definitely not stock fantasy, Planescapeead Gods about as far from stock fantasy as you can get, X2 had dog men with French accents and then X1 is again about as far from stock fantasy as you can get.

9 of the top 16 are outside what you consider fantasy. Over half. From all periods of the game. The idea that D&D was ever about genre emulation is silly.

Gates of Firestorm Peak is also pretty firmly entrenched in Lovecraftian Horror rather than Fantasy. Its the adventure that introduced the Far Realm, and its BBEG was an Alienist.
That makes 10.

I agree with Hussar completely. D&D was never pure fantasy from the start. To claim otherwise is to ignore a veritable motherlode of evidence to the contrary.