Stark didn't change the rules. The scepter relied on skin contact, likely something sub-dermal, to activate. Stark's got a big ol' mini reactor where his skin should be. It's not an asspull, it's a technicality.
Thor's hammer stopped working in Thor 1 because he was no longer worthy. That's how the hammer works.
Hulk learned to control his powers to a limited degree because Black Widow was helping him between movies, and he cares deep enough for her to let her have some sort of control over the Big Guy.
Saw 1 had a pair of kidnapped, slightly panicked and traumatized people in a cell with a corpse. Your first thoughts will generally not be "hmm, better examine it to make sure" but instead "holy shit I'm going to fucking die, we've been kidnapped by the Jigsaw killer."
Zod wanting to terraform earth wasn't just for the practical nature, it was to exert dominance over weak humans, and to strike a blow at Kal for thinking they were worth anything but subjugation or extinction.
Not all motivations have to be stated to be clear.
Thor's hammer stopped working in Thor 1 because he was no longer worthy. That's how the hammer works.
Hulk learned to control his powers to a limited degree because Black Widow was helping him between movies, and he cares deep enough for her to let her have some sort of control over the Big Guy.
Saw 1 had a pair of kidnapped, slightly panicked and traumatized people in a cell with a corpse. Your first thoughts will generally not be "hmm, better examine it to make sure" but instead "holy shit I'm going to fucking die, we've been kidnapped by the Jigsaw killer."
Zod wanting to terraform earth wasn't just for the practical nature, it was to exert dominance over weak humans, and to strike a blow at Kal for thinking they were worth anything but subjugation or extinction.
Not all motivations have to be stated to be clear.