Forgive me if I am putting this in the wrong place, but this seemed like the place to put it.
For me, I would like the ability to create an entire party of custom characters to go solo questing with. I used to do that all the time in previous D&D RPGs. Not that I don't like the current companions, they're very well done... It's just that a low level character with a high level background story breaks the entire thing for me. All of the current companions have histories befitting 12th-20th level characters (if not higher), yet they are 1st level at the start??? Just let me make my own companions that don't have backgrounds if that's the case. RPGs are a pretty solitary thing for me on PC, so I'm not going to be gaming with other living people. A Custom companion (or preferably a party of them) is going to be my best option.
I tried the suggestion of an evil playthrough, and just found that there weren't really any evil options available. There was plenty of mean, petty, irrational, and outright suicidal choices available. There just weren't any options that I would consider "evil." Take the two siblings you find in the woods with their nearly dead "true soul" brother as an example. Good of the brother to hand you full control of those two lackwits. Too bad you cannot exploit that for anything truly fun. You cannot make them your complete pawns. You cannot trick them into believing the absolute sent you because the Drow woman had strayed from the path. You can't make them drink poison. You can't even have them kneel and close their eyes in a trust exercise so you can slay them effortlessly. You can't pick up their brother's tadpole and put it in one of their eyes. Nothing. Even if you beat them unconscious you cannot tie them up, torture them for information, or do anything else that would qualify as evil. Personally, if I were doing truly evil I'd be going forward from that encounter with as much information as they could've told me and I'd be wearing gloves made from the skin of one of them and leading the other one around on a leash. I'd only pop the gag I made from their sibling's femur out of their mouth when it suited me, and... you get the idea. I actually enjoy being the somewhat good guy, who saves just about everyone that doesn't annoy him (and often for a very reasonable price), so it really doesn't bother me that the truly evil options don't exist... but if you're going to ask me to go there, give me a there to go to.
As usual, I cannot let an opportunity to pitch for the addition of rolled stats slip away either. I cannot express enough how much the current system for stats in character creation bothers me. What I usually aim for in terms of stats on a PC RPG is much higher than what I'd be happy to play with in a tabletop setting. In most every case I'm left with a character that, were I to be playing tabletop with those stats, I would have my character strip naked and run screaming into a pack of hungry ghouls 5 minutes into the session... just so I could roll up another character.
Oh, and as long as I am on my soapbox of requests... If you're going to go through the trouble of saving Sassa's miserable life it would be fitting to get a chance to recruit her as a camp follower, a companion, a slave (love or otherwise), or something... Perhaps you could make her go to camp and cook for you, I dunno... Something would be better than nothing.
About brother and sister.. You can send them to owlbear for "revenge" and use them as "meat" in this battle. This choice is approved by Astarion. Basically you use them as your pawns, Astarion correctly notices that they are incredibly stupid. It would be strange if Larian gave you 10 options with the same outcome. They will die from owlbear if you don't protect them, of course.
But I agree with you that the "evil way" is very weak. And MC evil actions mostly "stupid".