True, there's a certain intellectual interest in classifying variations on type, whether good or bad in rendition, rather like noticing that this fairy tale is a variant of Cinderella with a helper to get her to the ball rather like Rumpelstiltskin, but it's not what I read the stories for.
You get the same problem with historical fiction, where the characters are more tightly bound (even though the information is likely to be more minimal) and events fixed that the story has to drape itself about like a rose bush on a badly built trellis. (And badly built it usually is for story purposes.) When the information is minimal enough that wildly varying interpretations are possible -- did the emperor execute his oldest son and his wife for good reasons or bad? when not even the declared crime has come down in history -- it's a bit hard to read every new interpretation without the old ones whispering over your shoulder and breaking suspension of disbelief. But if it's the same old, same old. . .
Though one thing always gets me is the people who try to mix historical fiction and King Arthur (or even, sometimes, Robin Hood). A gritty realistic portrayal of character such as Galahad, or Maid Marian, really were like before the myth-making began. And I'm reading and thinking, You do know that this character did not have an original, because the myth-making was well underway before this character was added to the mix?