Every time people lament changes to the lore that amount to “not every member of species X is irredeemably evil” and claim the game is removing villains from it, I think how villains of so-caleld evil species fall into two cathegories: a) bland and boring and b)have something else, unrelated to their species going on for them, that makes them interesting.
I would say that many Mind Flayer villains are quite interesting because they are Mind Flayers.
Personally don’t really find the snack sized Cthulhu aspect that interesting. What really interests me about them is the lore about them once being a great empire of douchebags who were overthrown by those they oppressed (gith) who then took their place politically and now hunt them down. Says a lot BG3 focused on this lore over the Cthulhu monster aspect. Just some good lore building which could have (and I’m sure has) gone to any other races.