Monster taxonomy and organization

It seems that the new 2025 Monster Manual organizes EACH  monster alphabetically. This means a "Green Dragon" is found under "G". In the 2014 Monster Manual (and most MMs before that), all dragons were found under "D", for dragon. The same happens with giants, demons, etc.

I think this is an awful decision.

Not that this is simple. One reason there's so much debate over monster classification (and issues like orcs being inherently evil) is that taxonomy itself is complex. In the real world, we classify living beings into categories like Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species. Can a green dragon interbreed with a red dragon? There is no "right" answer, but I'd guess they can. What about a gold dragon? Applying real taxonomy to fantasy creatures is not easy or ideal.

But let's look at this from a practical standpoint

Should we have one single entry for each species? That is impossible because we need many entries for humans (bandits, clerics, druids, etc.).

Besides real taxonomy, how can we organize monsters?

One alternative I really like is monster type. This is one of the main points of my Teratogenicon. Undead have LOTS in common to each other, and if you ever want to create your won, looking at existing undead is more useful than calculating CR.

There are other practical reasons to use monster type.

First, let's assume you are new to D&D, and you don't really know the difference between demons and devils. Or maybe you vaguely remember playing 2e and you don't even KNOW there are monsters called either of these things.

You go looking for an explanation in the MM. You turn to "D" and... there is nothing.

Can you see the problem?

On the other hand, let's say you're an experienced DM and you want to build your own dungeon! This is going to be a hellish cave, full of demons... Now let's find some o populate it! Where do you look for them? Again, you've got nothing. At best, the MM has a list of "fiends" that include demons, devils and others.

And what if - unimaginable though it is - you forget the name of a particular demon you once saw and want to use as the villain?

The only way this is useful is if you use strictly for reference. You never create your own adventures, but maybe you're running a module that lists "1d4 green dragons" on the encounter table and you have to check it in the MM (that is not great either; most adventures should provide you with the relevant stats to avoid page-flipping and book-flipping, but modern D&D is so crunchy that this is nearly impossible).

This might be a radical, but I think a good MM could be divided in 20ish chapters, including the 14 monster types with a few subdivisions. For example:

Aberration

Beast

(Giant beasts)

Celestial

Construct

(Golems)

Dragon

(True dragons)

Elemental

(True elementals)

Fey

Fiend

(Explaining differences between demons, devils, etc.)

Giant

(True giants)

Humanoid

(maybe separate species from professions)

Monstrosity

Ooze

Plant

Undead

(maybe corporeal/incorporeal)

To clarify, "true" dragons, elementals and giants have that word in their names: e.g., Green Dragon, Hill Giant. To make things even clearer, D&D could use different names for wyverns and trolls. For example, "draconians", "dragon-like", "draconic creatures", "gigantic humanoids" (notice that troll is a "giant" but "giant bat" is not).

Calling a wyvern a "dragon" makes the idea of "natural language" impossible, since you'd have to explain (or assume) the meaning of the word "dragon" every time you find a "dragon-slaying sword", etc.

There are a few obvious problems to this approach.

First, the monstrosities are so numerous that the alphabetical approach just feels easier. In addition, they are not always easy to separate from aberrations (gricks and grells - what are they?). In fact, when I wrote Teratogenicon I had to go back to 3e to find a good definition of aberrations.

Some subdivisions would need further reflection. Should dragons be listed alphabetically, or should chromatic dragons be separated from metallic? Not sure.

But, from a learning or world-building approach, this would be nearly perfect. 

It also gives the MM a more "in universe" feel. When an average peasant sees a "dragon", "green" is not the first thing that comes to mind. Similarly, a "death knight" is an undead first, and for the untrained eyes it is not that different than other ghosts or apparitions. People will just run and call this place "cursed"!

The "monster type" division, therefore, is also teleological.

In addition, you could easily create an alphabetical index of each creature for easy referencing (with page numbers, of course), and this list could include both "dragons" and "green dragons", under D and G. You could add page numbers to modules and encounter tables too, but maybe that'd be too much to ask...

In conclusion, I dislike the new organization. It makes it more difficult to find some monsters and put them into proper context. It makes the game less coherent and more difficult to learn. I will not say I have the perfect answer, but I can say I find the former approach preferable to the current mess.