So this is definitely an interesting topic of discussion. From a gameplay standpoint, the vast majority of the mobs in the old game, while they had different models, basically did the same thing (with the exception of the corrupted models/aberrations in the Wilds and some small mechanics like the poison from the Spiders/Wasps). Almost all were melee attackers that would just run up to you and stand there and do a simple attack, possibly adding a status effect.
In Reborn, our goal was to make it so that generally speaking all the mobs in the game had a unique and interesting mechanic (or multiple mechanics) for the player to deal with. That’s why you’ll notice that the Chaos Tear casters have a different mechanic than the Scav Casters, for example. The downside to this approach is, of course, that we have to spend a lot more time on each creature type because they have unique mechanics.
So I think part of the question is, are we talking about world decoration here or are we talking about gameplay challenge? Because I actually think the variety in gameplay challenge of the overworld creatures is much higher in Reborn, especially once you get into the higher-level zones where some of the enemy types start to overlap and form different groups that lead to interesting crossover.
But from a world decoration standpoint, it’s true that while there are actually something like 30 unique “enemies” to fight in Reborn (e.g. 4 types of chaos tear creatures, 4 types of scavs, 3 types of giants walking around, dungeon minions, a few enemies that weren’t in the last Beta, etc.), which is about as many as the last game had, since they are all grouped much more closely into each enemy “type” from a design standpoint, it probably feels like there is less variety. So basically, a spider looks really different than a wasp, even if they both had only one basic attack and had the exact same combat mechanic.
We are doing some work right now to address the world decoration part of it by bringing back in some of the wildlife creatures; however, what I’m leaning more on those is making them passive (in that they won’t aggro you unless attacked) and then just having them fight back with more basic attacks. So they would be more about making the world more alive and adding some variety, maybe they are a source of some ingredients and resources but they don’t fill the same role as a full-blown enemy type in Reborn.