Yeah, I'm not sure what the "evil" path is even about. When I went to the Goblin camp and it was presented to me, my first thought was "Why? Why is this a choice? Why would I do this?"
It's like the evil character is meant to be stupid or just do things for no reason.
IMO, better evil dilemmas would Auntie Ethel giving power or knowledge for eliminating the brothers. Kagha offering their magic to limit the ceremorophisis process and giving more chances to use its power without transforming in exchange for eliminating the Teiflings or forcing them out, knowing it's likely their deaths.
Give me, the player, some gameplay bonuses and the PC some powers like more abilities or the ability to use the worm more without consequence to the PC in exchange for doing "evil" things.
You can even layer choices. Kagha offers some powers or influence throughout the rest of the game for some evil act. You do the act and find she lied or used you, you then get the option to use the Goblins to wipe out the Grove for revenge and to show that you shouldn't be used or mislead.
In the Goblin camp you're able to kill these absolute people, why not give the PC the ability to fight them and then force them to obey you instead. Hell, for the scenes with characters like Minthara they could make it an abuse of the characters power and position instead.
Edit: In Fallout 2 I could play all the families, gain their trust and use them, then sell them out to the next family. I could bone the Bishop family leader's wife and daughter. Those are more evil choices that to me make sense.