It was a revelation to my students that most non-canonical works are not written by women or working class people, or racial minorities. Most of the non-canon is simply not canonical for no particularly socially or politically relevant reason. To study the non-canon, in fact, you have to make an argument for the value or interest of the material, usually on social, political, or "cultural" grounds.
It is hard to make an argument for Cozzens or Auchincloss, or Anthony Powell. It's not sexy like mass culture is (Madonna in her day). The "mid-list" is non-canonical because it is neither high prestige high modern stuff, or subversive counter-culture, or trendy in any way.
It struck me that the duende is the same as "magical realism." In other words, the key to Hispanic Culture for the English Department. We might make the composite figure Federico García Márquez or Gabriel García Lorca to explain this convergence. (I was reading Sylvia Molloy's article in Moraña's Ideologies of Hispanism).