I apologize in advance for the Trollesque comment, but:
Bug: When the player moves, the monsters stay still
Expected behaviour: The monsters should be able to move as well
Having an asymmetric gameplay between the monsters and the player is the core of this game's design.
It can't be compared to other RPGs (Final Fantasy, Baldur's Gate, Divinity Original Sin to cite a few) where
the player and the enemies follow the same rules and have the same effects apply to them.
For the same reason, (and it was already discussed earlier on this thread) monster classes don't really have
exactly the same traits as their enemy counterparts, because that would just not work.
The Half-Dragon has magical attack like the Dragonspawns, but was given knockback as a source of physical damage (+ that makes an interesting design)
Player's Deathgaze doesn't work like monster Deathgaze, simply because it would be too strong (just prep conversion stone and maximize your CP to get 80% deathgaze, then fireball an enemy and finish him)
Player's Lifesteal and enemy's Lifesteal doesn work the same way at all either, the monster should absorb a portion of the damage he deals to you, not drink your health when you reveal him.
All in all, these are all design decision. They make sense because it remains coherent lore-wise, event if two distinct effects (like PlayerLifesteal and EnemyLifesteal) have the same name in-game.
I do agree that having enemies being affected by corrosion pools could have been a nice touch, but it wouldn't have been super effective and like shade say it would have made corrosive bloodpools much less troublesome for the player, especially in Rock Garden where some corrosive plants blocking a corridor sometimes force you to step on corrosive pools.