I know some argue that it's because love changed Simon, and Nia, but I don't see it that way. Take away Simon, and Nia is still a princess who questions everything. Take Simon away, and you have nothing. He was an empty shell. He yelled, he made flashy moves, and glorious promises, like he would save Nia and the universe, or he would never forget those who died for him.
But in the end he killed all those courageous men who followed him for nothing. He broke all his promises. He never saved Nia, he left the protection of the universe to others, and Zoushi, Kidd, Ailack, Makken, Jouken, Barinbou, and Kittan lie in barely marked graves while Nia has in immaculate grave site that according to the writer Simon provides with flowers on a weekly basis.
I realize this is exactly how the writer wanted it. They wanted to show people are flawed, they get old, and youth is reckless. And Simon was brilliantly written. But I still can't consider him a true super robot hero.
I know my opinion does not match the consensus, and will get me trolled. But that is how I see it.