I think grading matrixes would be well served it they assess the writing ability of the person. That is, how well can they justify their opinion with quotes and sources, rather than what the interpretation outcome itself.
the bigger issue was that this interaction negatively affected my relationship with the professor.. who was unaware of il filastrato as a source for chaucer?!, and unimpressed that i read two supplemental works that were beyond the scope of the course syllabus
also frustratingly tainted my association with shakespeare since whenever someone talks about academic shakespeare i immediately want to monologue