The evil endings in particular leave much to be desired. Just rolling to credits after saying
with no epilogue, not even Dragon Age or Mass Effect style slides is hugely underwhelming.
And some endings I'd posit need reworked entirely. Gale's in particular. At least leave some ambiguity, you can't just have
all his evil endings like "rocks fall everyone dies." If he tries to take Mystra's domain, sure, bad end. But the same exact bad end if he just wants to be a god of his own domain? C'mon! That's so disappointing. Imagine playing hundreds of hours only to be hit with that if you aren't just a simp for your goddess in the end.
And Karlach. For the love of all the gods. Why can
nothing be done for her? We have literal gods in the equation. If Gale can have a new body made and his soul restored you're telling me someone can't replace the poor woman's heart? A single true resurrection scroll, which Gale has I'll add, could resolve her issue entirely. That's not even taking into consideration things like Elminster, or wish spells, pacts with devils, and so forth. Like you're telling me we can't make a deal with Raphael to give him the Crown of Karsus to fix Karlach's heart? Really? Really really?
And Shadowheart. She doesn't even get a thematic ending. Not even
It's just the same a generic endings a custom character can have. Though she's got issues in general, like acting upset at
the Dark Urge wanting to slaughter everything
when slaughtering everything is in fact Shar's goal as well. Even after she's committed to her.
There are only really three major flaws with the game (which is easily GotY for me), and this is one of them. The other two are: not having some kind of action to clean up and wipe your face (create water is a workaround but silly that it's needed), and the main character not being voiced or having animated dialog makes them feel soulless and lobotomized, especially if they're origin characters you've seen what they could be (as followers) and what they're then reduced to (as main characters).
Fleshed out and reworked endings and a "clean" action I think are very doable. The MC getting voice acting and animated dialog probably isn't happening at this point. But that's 2 out of 3 that are very fixable.