A Drow who already grew up thinking he is superior and is witnessing a half-elf failing at a door will let her belittle him and politely ask for her help? If you just stay neutral she goes on her own path, doesn't even try to convince you to work together. Astarion jumps at his throat and fails miserably - and I invite him to camp? Why the hell would anyone even neutral trust him?
I actually didn't think of this (I recruited the companions based on what I already knew of their personalities). The only character I'd see myself wanted to be with in that situation is Lae'zel, since as evil characters we would both not be bothered by helping others and she shows that right away. I feel like if there was just a bit more variety in the dialogue during their intro scenes that could show off what personality/intent they have, it would be greatly improved. For example, Astarion could be watching a fisherman struggle against an one of the little brain things, cheering them both on enthusiastically but doing nothing to intervene. This shows off more of his "I don't give a shit, I just want to see what would happen" demeanor that he has during most side quests that don't involve him, and that way if I'm roleplaying as someone of similar alignment I could see that and think "finally, something *fun*," and get along with him almost immediately.