The Bewitch Question

Unfortunately, if given great powers I don't think I'd be greatly responsible.  I don't think many of us would be.  Sometimes, that's a maddening thing in fiction.  Why DOES samantha let herself be the world's door mat?  Why doesn't Superman try to stop all war? 

On the other hand, sometimes it is the thing that makes them the hero.  It's cool that Spiderman doesn't go on the speaking circuit or merchandises himself beyond the odd photograph.  It's a mark of restraint that Superman doesn't push Lex Luthor through a wall. 

Maybe I wouldn't be a good person with unlimited power, but I can imagine better.