I would say that the presence of annoyingly stereotypical characters is precisely that. A Priestess of Shar absent depth, a Gith warrior who is unsurprisingly chaotic evil to the point of behaving as a monolith, a vampire spawn who creeps about in textbook fashion. I can go on, but my point of contention with the supporting characters is that they behave so woefully generic, that it's as if somebody just pulled them out of the sample sections for the PHB (or MM, depending on what character you're referring to). Maybe individual quirks will be better exhibited later on in the game? Who knows? But at its current state, that is a point of concern I have regarding the characters, as they sit. This is a feedback section, after all, and this is the feedback I am providing.
I would actually say Shadowheart has the most depth out of any of the companions. But she takes a while to open up, probably why a lot of players are missing out on her story beats. There's a lot of potential in her for a complex storyline.
As for playing an evil playthrough, yes, the devs were wanting feedback specifically on evil choices, according to them players prefer to be good and that results in less data than they'd like on evil companions and choices.
https://screenrant.com/baldurs-gate-3-release-good-evil-playthrough-differences/ From what I've heard, there's 12 writers each working on a companion, 2 have 2 companions, so 14 companions in all. We got the evil/neutral characters first because in a build that includes the good companions, they would probably be left in camp and not get feedback. A dataminer's already found 3 new companions in the code.
As for your rather general feedback, I want to ask what exactly would make the story more compelling to you, or more refined? What story beats are pushing you away? How would you change the companions, or what sort of companion would you want? Not to be rude but a rather generic "The story isn't compelling" isn't very helpful feedback.
