I didn't like how they handled Zodiark either, but for different reasons, I think.

Considering how he was worshipped as the ancient's savior, I didn't really expect him to look so.....obviously evil. Tbh, I was kinda hoping there'd be some flashback somewhere that shows Zodiark wasn't actually a bad guy and genuinely cared about his people and had his own reasoning and views of things, and some just happen to clash with Hydaelyn's, maybe even having him - or rather, the thousands of souls that made him up - being aware that by ironically being imprisoned, they were doing the planet a favor.... (The Cluster from Steven Universe rings a bell there? lol). The whole trial could've been about trying and failing to save Zodiark from Zenos and Fandaniel, but nope, we got "generic big bad not-Satan" instead /sigh oh well....