I think there's been a misunderstanding. I mean that regular mobs should have ranged attacks, climbing, and other interesting methods of combat/maneuvering. You can keep putting in land-based melee animals, but that's unnecessarily limited. You need more to fight, and not just during a temporal storm.
And if the temporal mobs aren't crazy, then what is? The game is fairly grounded outside of the lovecraftian stuff, so that's the only design space you have to really play around in when it comes to enemies. And in order for "fear of the unknown" to mean anything, there has to be a payoff. Surface drifters simply aren't scary once you realize how easy they are to kite once you have a flint spear. Even during temporal storms, when things are at their wildest, you can just make a dirt pillar and watch everything go all weird for a while and be completely safe. There's nothing to be afraid of. Now imagine if during a temporal storm you had swarms of flying locusts descend upon your base. Horrible tentacle beasts writhing free from the earth beneath you. Complete and utter madness where no place is truly safe. That's what you expect when you hear a lovecraftian storm is approaching, not some blinking dudes you can easily ignore with no investment into a base whatsoever.
EDIT: I mean come on, a voxel-based lovecraftian game is begging for some hounds of tindalos. Oh, you have a 2x2x2 doorless bunker buried deep in the earth? You thought that would save you?