Warbreaker wasn't dark, Nalthis was.
The system of BioChromatic Breath means there's systematic exploitation of the poor in order to gather Breaths. We saw examples of how giving up Breath felt, it is something intrinsic to people that they were born with. On top of that the Returned, even in the country where they are treated the best: as gods, they are expected to die again in order to heal someone. It's a constant guilt-trip till that decision. Elsewhere they are prejudiced against, exploited for use of their Divine Breath, die within a week. If they want to survive beyond a week? Breath.
The setting of Nalthis, though colourful is very, very dark
Please watch out for typos "I tje" and state the full form "SSC" of your abbreviation for the first instance so people know what it stands for.
I admit that these are possibilities within the setting, my point is that it seems narratively unlikely.
I think @aneonfoxtribute was referring to the God King's lineage