It's very common for criterion (rows) within a rubric to have different levels of importance. It would be extremely useful to be able to weight criterion (rows) with a percentage (much like how the Turnitin rubric allows). Although you can tweak the points for each criteria (cell) this quickly becomes fiddly for even a moderately complex rubric. Row weightings would allow the points to remain the same in each criterion but only affect the calculation of grades. This would make the tool a lot more usable and transparent.