I'm not particularly surprised by the results of the poll. Abelard is well-written, even if the lines given to him start to drop significantly after Chapter 2. Cassia was probably someone's waifu as she keeps having stuff to do and to say constantly ( compare and contrast with Argenta's questline, that is essentially two maps cobbled together and a result based on stuff you have no way to know, her becoming a Repentia or getting the Holy Armour in a quest you don't see resolved offscreen is based on hidden stats you can't know). It helps that both Cassia and Argenta are absolute monsters in combat and they could solo everything at release. Also Murder Disney Princess.
Pasqal is written decently and was mechanically broken, not surprised he got attention. Decent sidequest too.
Heinrix has the problem of being Abelard 2.0 with shittier writing. Yrliet has the bonus of being mechanically useful and people want to fuck the redhead elf even if she's written horrifically and has the biggest Woman Moment of all the game. She's a retard but people simply want to fuck the elf. Marazhai has a similar problem to Heinrix, he's essentially mechanically useless for when you get him, kinda weak compared to the powerhouses.... but at least his writing was funny, before I sent him to the dungeons.
Jae and Indira, with the extra of being the token minorities, were truly dreadfully written. We're supposed to find Jae "cool" and Indira "a different point of view" but they're both self-centered annoying heretics, and most people play Lawful Good in RPGs. A foregone conclusion.
What strikes me are the NPCs and Boss Fights. Not surprising most people remember the Chaos Marine because I bet more than 50% dropped the game in Act II and very few managed to struggle amongst the sea of mediocrity until the other bosses, but the NPCs are telling: Xavier is essentially dumped on you endlessly through Chapter IV-V (being the real cobbled together endgame) and Winterscale is the only one with a sort of arc and resolution.