Anyway, the answer is that we used to have exactly that feature. The predecessor to Studies, Mental Case, had the total number, and the due number. The problem is you get a lot of clutter. Every row has a number.
So what we decided was that the 'due' number is the really important one, and put that there. We put the total number at the top of the right panel when you select the row. The All Notes also has the total number, because otherwise it would just duplicate Due Notes.
Hope that at least explains why we did it, even if it is not totally satisfying.
"So what we decided was that the 'due' number is the really important one"
Yes, maybe it is, but i doubt thats the right place to put it. I guess thats learnt from other apps.. Have a look at the screenshot, I mean .. wtf?