I agree, it didn't fit well. I suppose they couldn't really think of a better way of telling us that Orin and Gortash were at odds after Ketheric's demise. But then again, when we do meet Gortash he says it himself anyhow before requesting an alliance, so I'm not entirely sure why it was required. If anything, I think it would've been more epic had it not been revealed until Gortash's coronation.
