Yes, Perdid, people like to read about violent action characters.  Take the Avengers movie.  It has the Hulk, Thor, and Black Widow (an assassin).  Its done well at the box office with that line up, precisely because people are not into "nice characters".  Even Jean, though she was a good girl as Marvel Girl and as plain Jean Grey, is most famous for being Phoenix.  As the Phoenix she can be ruthless and destructive.

Even look at a nice character like Colossus.  Marvel made him the Juggernaught, and as a result he now as a dark side.  Magik, his sister, is a powerful and shady sorceress (her mutant power is space/time energy warping).  Marvel is a business first and foremost.