Nigga are you fucking retarded?
Why didn't fucking IROH the hero of blah blah blah step in and destroy his brother or step in and cast down his crazy as shit niece?
Both continued a path of destruction and the latter was a fucking lunatic that would have lead the fire nation and world down a path of carnage and destruction for generations.
Why in the fuck would they follow fucking Zuko? A nigga who can't even beat his crazy as shit sister and was cast out after being fucking humiliated by his even worse father?
He has no claim to the throne and no heroic deeds or anything to endear him to the public.
It would be seen as a wayward loser prince trying to take the throne from the rightful heir.
Bullshit writing pure and simple.