|Arthur Rackham |
(because one needs better goblins)
Still there are things to be said about monster design, and I agree with Mike Merles and 5E when they want to focus on the intangibles of their monsters: their behaviors, ecology, hooks related to them and similar inspirational information for the GM - up to a point. Monsters are iconic and a central theme to table top fantasy, and doing them well goes a long way towards doing a game well. The issue is - what's really useful and necessary in a monster design, especially one published as a supplement. For this I think to the games I've played recently and what makes encounters in them good.
I'm been playing in Ben of "Marazin's Garden's" Dreamlands game a bit and I have noticed that one of the things I enjoy is that we've yet to encounter any monster from a book, at least as far as description and characterization goes. To me this is a mark of a good campaign and good world building.
Using unique monsters means among other things that the GM needs to describe them and that the players need to think about them as more then a reference to a Monster Manual. One of my major complaints about published modules, and even the 5E Monster Manual, is a lack of description for monsters, beyond dull formalities. There is a balance in designing pre-made monsters, somewhere between several pages of (likely dull with Elminster invoked) of genre fiction the Volo's Guide promises and the terse statistics based descriptions found in the Little Brown Books. I'm not sure where exactly it lies, certainly Fire on the Velvet Horizon is pretty lyrical in its monster descriptions, but its a fun read because its descriptions are full of evocative detail that gets a GM thinking about how to use the monsters described within - and of course anything done well is better then the best thing done badly.
Personally however I have little use for Monster Manuals, even good ones. For me, the aesthetics of monsters aren't hard to think up and design, and the most important element about an encounter is that it makes sense in the setting. I tend to run non-standard settings, and making monsters that fit those settings, tell stories about the setting and generally provide a point for player interaction, wonder and decision making is often far easier then fitting monsters from other sources into a non-standard setting.