One of the major problems we have always had with the old gradebook was that students would have one or two assignments graded by their teacher, and then see that they had a total grade of something like 5.6% in the course. Our teachers would then get emails from students asking why they were failing the course. The fact that the total grade calculation includes non-graded assignments has caused significant confusion for both teachers and students at our schools. Our students expect to be told an average of the graded assignments only, and use that number as a measure of how they are doing in the course.
I was under the impression that the new gradebook would fix this longstanding issue, but 1.9 beta still appears to have this problem.
There is a setting to only "include non-empty grades" in averages, (as in
MDL-10480, I think), but this only seems to affect column averages, not row (student "total grade") averages.
Since that code regarding column averages is already in place, I assume that it is not too hard to add this option.