I also get the impression that there are character flaws which are considered cool, so it's ok if they go unchallenged as long as the character's backstory is tragic enough. (BBG Astarion is a prime example for that.)
I'm not necessarily sure thats a fair assumption. I think to be a bit more understanding, it's important to remember some issues will just speak more to certain people! And certainly personality traits will just be more off putting to certain people.
Would you be ok with it if I turned "cool" - which is admittedly slightly flippant - into "socially more acceptable" ?
With Karlach it is less her view on life (and what I think is deliberate self-deception in some points) that bothers me, but that it cannot be questioned. I think the only time you can call her out for something is when she complains about having to save Mizora's asset in order to save Wyll from eternal damnation. Otherwise she is allowed to the luxury not having to deal with a lot of things. In addition with how even the more cynical party members are only ever full of admiration or at least respect for her, I am left with the impression that this was mostly done to make her end more tragic but it unfortunately takes away a lot of the potential of the character too.
But that's just me, I generally prefer inner demons over the quick and easy solution to hit a bad guy and be done with it.
