The only one who should use a graphic novel in school might be K-2, to ensure competence and retention of the new language. Anyone beyond that grade should be reading progressively higher forms of English text. What will they all do when they have to read Legal and Medical journals; convert them into Graphic Novels; oh I forgot, we won't be producing any Doctors or Lawyers or Engineers, because THEY CAN'T READ!
Him I want to hit.
Regardless, I think I agree with the ignorant naysayers for this reason - Put comic books in school and you'll squash any interest in them. There's a reason most people seem to think classic literature, history, science and math are boring.