No character storywise would want to help goblins, even an evil one (smart evil one).
Yeah, they need to make it more appealing. The character I had who sided with them only did it because the grove was already wiped out due to the sequence of events earlier. There was no reason to not give away the location and a lot of reasons to make possible new allies. I suppose there could be some argument for Minthara being persuasive but still not a good enough reason to side with them. She and the goblin leaders need more dialogue.