I completely agree with all of this but I would add a few more specific points
Romantic interest or "High Approval Platonic" relationships should have unique cutscenes at the pre battle get together
That these above relationships have some reactivity beyond the random click animations during parts of the Final Battle - as in those members you take with you are literally your ride or die companions. I think we should show them some extra love in cutscenes no?
I can not agree with Point 1 more. Companion quests end very very quickly into Act 3. It leaves the world feeling very empty even though there are so many side quests, we are invested in these characters and thus feel the connection to the world through them.
Yes, I took that for granted but it is better to specify. Your romantic interest needs special reactions since in most cases your destiny is linked to theirs, and well, they are the person with whom you should be most intimate.
And of course if you are fucking evil you also have to have your consequences and appropriate ending, it cannot be that you murder half the city and brutalize their corpses to be the hero of Baldur's Gate. Give me consequences that I have played evil because I wanted to not because of an accident
Actually Dark Urge evil path is the only one viable evil playthrough because you get unique questline with rewards of gear/spells etc for murdering few particular innocents and Bhaal's path really fits the Dark Urge. You get some rewards and unique interactions, maybe not so much as I personally would like to but it's much better than "kill people have no rewards no consequences" stuff for another evil options.
Don't even underestimate an evil cleric raising go-go undead and throwing them at his loved ones, wonderful
By the way, that explosive ending of Gale needs a correction, the same as not being able to manipulate the emperor and Orpheus to collaborate together if you have great charisma or ask for help from our illicit good friend, he is also a magician, I doubt he would refuse to give us back the crown for Mystra (for us or Gale it wouldn't make any sense).
Another thing that I don't know if it is taken into account: shouldn't it be more difficult to resist the transformation if you have left your brain like a worm-based Gruyere cheese? I don't see it coherent that my characters get more damn worms with the problems you have with only 1, but in that case we should see some special option in this regard