Gale isn't evil. You have to succeed persuasion check or he leaves if you go with evil route in act 1. He's angry at us. So then you're stuck with Shadowheart, Lae'zel and Astarion, that is... if they are even alive. If not, well then... you have only generic mercenaries from Withers.
If someone manages to lose all origin characters before the act 1 party, I don't think it's Larian's fault for having no content.
Right. Then why is it okay to have "evil" characters on my good playthrough, but it is not okay to have "good" characters on my evil playthrough? Why the restrictions? This game just doesn't offer you anything if you don't play a morally good character to the letter.
Larian should really take some cues from Pathfinder Wrath of the Righteous. The game can change drastically depending how you play - good - neutral - evil. 4 playthroughs behind me and I still haven't seen everything the game has to offer and it's way longer than BG3. Not to mention companions - there are no restrictions with recruitement. Everyone can join, but that doesn't mean they will stay till the end. Too many decisions they don't like and shit will hit the fan. Or... we can even try and change their alignment, it won't work on everyone, but there's a chance. Now, this is what I call branching RPG with choices that matter.