Denzel Washington: Refuses to act in scripts where his character has a romantic relationship with white women. If they do, he asks for it to be changed (for example: The Pelican Brief, Man on Fire).
Samuel L. Jackson: Will do any shitty old script as long as he gets paid a lot of money for it. Thus, his name now has very little marquee value (see: Sphere, Formula 51, The Man).
Laurence Fishburne: Is now fat (see: Matrix Reloaded, Matrix Revolutions).
Morgan Freeman: Plays the wise old negro in every movie. (see: His entire filmography starting in the 1990s).
I don't think any of these guys qualify as icons!