Because who in good mind would recruit most of these companions in the way they are presented? I think only SH and Lae would make sense since you meet under certain circumstances that can create an easier bond to at least work together.
Shadowheart tried to murder my character, so nope. Though she is at least honest enough to admit how far she is willing to go for Shar.
Wyll and Gale are the only ones that didn't show any killing urges towards the main character so far.
She's a priestess of Shar. If she wasn't willing to murder some random jerkface who gets in the way of her divine mission of utmost importance then she would not be a priestess of Shar. If you made her attack you, you probably deserved it.
Wyll is a lying jerk with the most ridiculous pretense of not being a warlock despite dropping eldricht blasts everywhere. I don't even understand how his character is supposed to work, if we're supposed to pretend to not know that his character sheet says "WARLOCK!!!!!" and what he does in combat is the usual Hex & EB. Further, he's admitted that he wants to be a hero. He really, really wants to be a hero. So he made a tiny little deal with a devil and now he's a slave. What happens when his devil turns out to want us dead? Will he tolerate turning into a level whatever peasant with no powers or do as ordered?
And Gale is another lying jerk who is all jovial and nice and friendly, but actually he's a nuclear time bomb on legs and at any time he could wipe you out.
Our companions thus far are not exactly a nice bunch and there's plenty of argument for refining their attitudes a bit, to hammer and chisel away at their rough edges. Literally, if possible. But one can at least understand why most of them are the way they are, and their flaws do not make them entirely useless in a team. Gale is a bit of a risk, of course, and I would much rather have an Avariel cleric/mage with a soft voice and no damn time bomb ticking away, but it is what it is.
Astarion, meanwhile, is just a different kind of not very nice. I would say that I don't trust him any further than I can throw him, but given the mechanics of the game, I suppose that wouldn't be entirely accurate.
