this.
OP, your points as to what makes a character interesting are valid (i can personally attest to this as I'm about to release my ver own novel focused around high action martial arts) but you must remember that not every character can be a Naruto or Sasuke type.
However, therein lies the issue and presents the question- should people like itachi have a novel based on them in the first place?
now i haven't read any of the novels, but its fairly easy to understand why someone like naruto or sasuke would have a much more interesting story than someone like itachi
that being said, I'm not sure if it was just executed poorly, but i can foresee a engaging novel about itachi existing. Whether the one that exists is or not, is left to me actually reading it