Superheroes sure have made change in the past few decades, haven't they?
When the idea of Superman was conceived back in the 1930s, the character's creators (Jerry Siegel and Joe Shuster) weren't really trying to create a character with immense depth. They mostly just wanted to explore the idea of one man doing all these impossible yet incredible things. Super strength, super speed, flying, eye laser beams, freeze breath - pretty much anything that the writers could come up with at the time. But the medium has evolved since then.
The days of corny one-liners, silly storylines and goofy costumes have passed. Recently, writers have opted to explore the darker sides of superheroes. Sure, there are still people out there who look to Superman as a great hero, but readers today are more drawn to characters with internal conflict and moral debates.
What if they used their powers unethically? What if they performed questionable acts of violence? What if they were actually just villains pretending to be a hero? We all now know how twisted a person can become when given a sliver of power, but just how far can they step over the edge?