Twenty years ago my parents wouldn't know who the X-Men were, and now everybody knows that stuff. It means that deconstruction of the superhero is something you can do. All those movies have led to a point where we can finally have 'Watchmen' with a Superman character who doesn't want to save the world and a Batman who has trouble in bed.
The difference between 'Watchmen' and a normal comic book is this: With 'Batman's Gotham City,' you are transported to another world where that superhero makes sense; 'Watchmen' comes at it in a different way, it almost superimposes its heroes on your world, which then changes how you view your world through its prism.
I understand the rules of Superman - not necessarily better than anyone else - but better than a normal filmmaker would. After doing 'Watchmen' and digging that deep into the why of superheroes, when Superman is presented to you, I felt like I was in a unique position to say 'I get this guy. I know what this is.'