After playing through a couple times what is really standing out to me is that there is little 'team building' or bonding that you get to do apart from with the character you are romancing. Sure, there are companion quest lines where, basically, you choose to save their life or not. But the vast majority of your friendship/connection with others comes out if you are trying to sleep with them. I really think we should have options to bond with people and explore their character or influence their character just on the basis on friendship choices.
My first criticism is that we don't get to give the character a gift, which would be an easy way to boost approval with someone in Act 3 you may have been neglecting or not often including in your party. There are so many books strewn across the world and funny things like unique bottles of wine. For example, since Karlach always talks about her love of food and drink, gifting her a bottle of some riesling or ale just seems normal.
There are bits of each character's backstory I fully expected to explore either by turning up at a certain location or giving them a gift and this would have been a great opportunity to 'nudge' the character into agreeing with you about later choices or just better understanding each other. For example, if you're going to go to the hells, perhaps Wyll should want to join if Karlach is also going and he (Wyll) should talk TO HER, not your character, about making sure she's feeling alright about the journey. Laying the foundation that all these characters care about each other, you know? Similarly, we don't explore much of Gale apart from his past romance. I would love to gift him a book on spells or education or something and start a brief conversation about what brings him joy in magic. It would add some much needed depth. Right now, he's just a walking tragedy. Giving him such a book and having the other characters say "yes, that was nice" or approving would make more sense.
Astarion is similar - I kept expecting to be able to befriend him and build rapport in a way other than... sleeping with him. I really thought we'd be able to give him a gift of a painting of himself. Or, my main hope throughout the entire game, that we would be able to help reawaken memories of when he was a magistrate. That seems like such a nice piece of backstory left untouched. Cazador targeted him because he handed down decisions he disliked, which sort of implies Astarion was either a wise or merciful young judge. That would have been interesting to explore further. I would thoroughly want to encourage he reconnect with that thread of himself and having some other companion say "oh, you should give Astarion this book on legal history" and then approve when you do so would be the team building and group rapport I'm currently missing.
I realize there is only so much the team can build into this complex world, but right now it does feel like I'm keeping characters alive either to sleep with them or use as canon fodder. I'd much prefer to build them up - together - in a way that I care about they care about each other. Heck, it could be something as simple as characters suggesting a piece of armor or weapon is currently better suited to another character or checking in that the other person is doing okay at camp.