It's not the amount of monster books, but the portion of interesting monsters per book.
I completely agree.
Most of the compelling creatures informed by longstanding archetypes are covered in any edition's first monster book. Monsters in subsequent or third-party books tend to be extremely specific, modifications on tropes that are already covered, or ridiculous D&Disms. They're swanmays, boalisks, or wolfweres, respectively, to the more straightforward dryads, basilisks, and werewolves. And those kinds of odd creatures are fine in the context of a specific adventure (e.g. the marble snake in Palace of the SIlver Princess is great), a specific campaign setting, or, sometimes, if you happen to be really feelin' boalisks, but, to me, they don't come off as vital or compelling.
I rarely find more than a handful of monsters that make me go "wow, cool!" when reading a new monster manual. And I don't think that's because no compelling creatures informed by longstanding archetypes still exist to be invented/adopted into D&D. Rather, I feel like most monster manuals just don't have enough... I dunno... cowbell. But, of course, that's just my opinion. Ymmv, and I'm not here to tell anyone that their collection of monster manuals is bad.
I'd be curious to hear more of your thoughts about this
@Yora having read your
Fantasy Safari Series from several years back with its count of repeated cliches in monster manuals, i.e.:
Fiend Folio Cliche Creature Counter:
- Evil Apes: 2
- Variant Ghouls: 2
- Demon Dogs: 4
- Skeletons with Robes: 5
And to reiterate my point from above: all of those cliches are capital "A" Awesome (and variant mechanics to keep them interesting are all well and good). I just don't see the need for the fifth
named skeleton with robes that has its own description, picture, and bespoke place in the multiverse.