Why do actors who play iconic characters never get any good gigs?

Take The Sopranos cast for example. Outside of the show, the actors domt have any notable acting gigs. When they do get an acting it’s for underground movies or shows that domt get that much attention. You’re telling me people weren’t blown away by Christopher Moltisanti, Bobby and a lot of other great characters. This is barely scratching the surface. What about actors in Dexter, Smallvile, Breaking Bad?