I feel like the Death Star existing at all ruins all of Star Wars, from a certain point of view.
The Americans have built (and used) the nuke, what does everyone else do? They build their own, of course! Why doesn’t the Republic start building Death Stars after VI, or, better yet, why doesn’t the Empire build like 20 after their rise to power? Realistically the sequel trilogy should be about two sides having nuclear bombs pointed at each other yelling.
But it’s Star Wars, so it doesn’t need to make realistic, logical sense. The expanded universe tells us all the reasons that this doesn’t happen. Moviegoers don’t get that info, but they don’t care because the story is about the characters.
The Death Star is widely associated as a symbol of tyranny and mass genoicde. The rebellion fought to prevent those weapons from ever being constructed, so it stands to reason the republic wouldn’t even consider building another superweapon. Doing so would cause mass riots.
The Atomic Bomb is different because it has never been used by bad people. It’s two proper uses were the lesser of two evils at a time of world war. But if North Korea started decimating cities with no weapons, I’d bet the entire world would illegalize nukes once North Korea’s dealt with.
TLDR: The Empire abused the Death Star to promote fear and evil, while the US used nukes to end a war which Japan was clearly losing but refused to surrender.