Out of curiosity, are the articles with only fluff information about the KoK versions of generic D&D monsters (for CArc and MM3) even worth listing in the Index?
So it is a very good candidate to get included, even though the fluff text is just a spin on the original fluff text.
Most of the time, the criteria for inclusion in the index is "is there some sort of numerical/statistical information in the monster description?". So, for example, the entry for "Chicken" in
Dangerous Denizens: The Monsters of Tellene is included in the index, because although it is 99% fluff, the description says "An average chicken has 1 hit point"*.
Where a monster is mentioned without any sort of stats, it usually doesn't get indexed. I decided on that criteria up front simply to keep the scope of the indexing project vaguely manageable. I think if I had tried to index all the monster fluff in D&D history, I'd have abandoned the project years ago.
Of course, there are some exceptions to this general rule. All of the Ecology articles from Dragon magazine are indexed, even though many of them don't contain any stat blocks or number -- it just seemed wrong not to include all of those. And occasionally, I decided that a stats-free monster entry warranted a listing under the "Variation" category.
Based on that, and your descriptions Alzrius, the fluff articles about CArc and MM3 monsters in KoK probably won't get included, but the advanced horses probably will.
*Total aside: We keep chickens, specifically a breed that has historically been used for cock fighting, although we keep them only as pets (rather spoiled pets too!). I've had to separate boisterous young cockerels on many occasions, and I think that modeling a chicken as a creature with no attacks and just one hit point woefully underestimates how fierce an angry chicken can be!
Didn't the FR 3.0 - 3.5 monster update get in there? This is a very similar concept.
Yes, because the updates contain crunchy goodness.
Creatures that got 3.5 updates appear twice in the index. The aarakocra, for example, is listed once as a 3.0 creature with "
Monsters of Faerûn" as the source, and again as a 3.5 creature with "
Monsters of Faerûn + Monster Update (A Web Enhancement for the Forgotten Realms Player's Guide to Faerûn Accessory)" as the source.