I don't disagree with the OP that the choice is a bit black and white, and would more interesting if the choice was difficult.
And let's be clear: the goblins we meet in BG3 ARE evil. You find them tormenting a gnome. You go the Camp and they are celebrating the kills and kidnappings in Waukeen's rest. They are actively trying to find a group of people minding their own druid business so they can destroy them. They are roasting and eating a person. They sell people into slavery and one of the bosses tries to drug and enslave Tav. They are tormenting a baby animal, Halsin, and an adventurer after killing his friends. Of course Halsin will kill the goblin children who were throwing sharp rocks at him! If you go to Mountain Pass without killing the bosses, he's dead in his cell -- the kids killed him. The bosses are tadpoled but the goblins are not, making them fully responsible for what they choose to do.
Those are not actions that are just part of their culture. They actively harm others and enjoy it and it's certainly not something we'd just excuse in RL. "Oh that serial killer? They aren't bad, they were just brought up that way."
A good portion of the druids are racist xenophobes and ineffectual to boot. They are hard to side with. But even Kagha fundamentally just wants the tieflings to not be her problem so she can lock off the Grove from danger.
This is all an excellent point. Sure the goblin leaders are mind-controlled, but not all the goblins are. They don't have to roastand eat the dwarf, they don't have to enjoy what they do. They're evil by most decent standards and while genocide isn't a morally spotless choice, it's the choice that's justifiable in this context, the opposite choice simply is not. There is a question of HOW you would make this choice more difficult? Let' look at thisfromahighlevel. You have minions of the main antagonist, an antagonist that is not meant to be at all sympathetic. This conflict is meant to be our first look at the greater antagonist and the threat they pose. So I think that this could go one of two ways, remembering that this first conflict is meant in part to show how great the threat is. First is what we have here, the minions are cruel and evil and showcase the evil of their master. The second approach (as I can see it) is that the minions are all decent folks who have been mind-controlled into evil entirely. I think that in that iteration the most likely way things play out is you have a choice between freeing the goblins in a way that sacrifices the tieflings/grove (I think keeping them as goblins is a good call here. They could have been a tribe that wanted to be more peaceful and mind their own business, but were enthralled, so it seems like they're typical goblins but if you look beneath the surface things get more complicated) or saving the tieflings and killing the goblns. I don't think this is inherently better than what we got. Yes it's a harder moral choice, but harder doesn't automatically mean better.
Firstly, I remember reading that Larian framed act 1 the way they did to get players comfortable for the darker turn things take in act 2 and beyond. I think setting up those expectations and then showing how complex things can get later is a valid choice. Secondly there's a broader story point to consider. Ifthey went with that approach, then they can't have the "infiltrate the cult" option since by freeing the goblins, you're breaking them from the cult. If they wanted to preserve that option then they would introduce an option for letting the goblins stay controlled, which then in itself becomes just the fully evil option, because there's no way to justify killing innocent bystanders and leaving a group mentally subjugated.