If all the other celestial avatars were freed, (or any number of them), I;d garauntee they'd be mucking around and causing disastrous events just as bad as Odin was.Alex needs a vessel to enter this world, I'd guess because his protocrystal wasn't broken like Odin and he can't freely roam. He kind of sucks though regardless, he opposes Odin but is almost as bad as him, wanting complete worship to him and subjugation (Based on the final toau and alex bcnm fight dialog.) They're both two bad extremes that only hate each other because they're opposites.
Altana/Promathia are more the gods of total life and death than dark and light. Odin and Alex are more the extremes of evil and good.
I wouldn't call any of them "good or bad", they just don't give a fuck about humans, so anything they do to them is inconsequential. (see stepping on ants analogy)
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