Zodiark was never portrayed as 'evil' and is one of the reasons as to why the Sundered even exist. Both due to reversing the effects of the original Final Days and due to acting as a shield against their return even after the Sundering took place. I didn't find his appearance to be particularly sinister in nature - to me he simply looked powerful and refined and fairly close to how I'd imagine a giant Xaela with a body covered completely in scales.

Let's also not forget that the developers themselves have frequently stated that what is 'good' and 'bad' in the story is very much open to personal interpretation and a matter of perspective.

So, each to their own!