This distinction has been brought up many times by many people, though not as much in reference to gaming, and not in so many words. The gist of this distinction is historical: Epic protagonists from ancient sagas like Gilgamesh and Beowulf do not undergo the same kind of psychological change and examination that modern ones do. Gilgamesh is what he is, and his story does not examine or care about the choices he makes nearly as much as their consequences. A lot of creation myths and parables also fit this pattern. When the character is well-defined and consequences are interesting, it can make for a decent story.
The more interesting story in my mind is the one that examines the protagonist’s choices and their motivation. Consequences figure into their psychology, and their future choices, but aren’t the focus of the story. I want to know who this protagonist is, what makes him great, and why he has decided to use his talents the way he does. If Gilgamesh is a good example of an Epic protagonist, then Gregory House might be a good example of a modern one. In the show, his actions are largely secondary to the motivations he has for them. Other characters spend the majority of the show analyzing and overanalyzing his motives, emotions and affect.