Oden was born to be boiled while Kurozumi i.e Coal was born to be burned is poetic but brain dead people overreacting as if they matter.
Everybody sees what Oda intended; but we also see how horrid it is.
Oden was just an individual, but the Kurozumis are a whole clan. Orochi and Kanjuro both grew evil because of this; now you have entire kids, the literal future of the country, happily cheering for the message that the entire clan they prosecuted to death just for the sins of a father deserved it.
Ace grew suicidal because of the kind of ideas Wano's teacher is passing to his students through Hiyori. It's just out of place for Oda.