I would /hopefully/ suspect that the additional letter is of high value? It's hard to show the work you've put in to your graduate degree just by stating it on your CV, especially if you are doing your Masters. The majority of Master's students don't submit papers until they are at least almost finished. I can't speak on behalf of PhD students though. But that's where the supervisor can speak on your behalf and state that he/she WILL be submitting papers, presenting at conferences, etc.
I'm in my 2nd year of my Master's and I was lucky enough to submit a first-authored paper last summer (accepted soon) and present an oral abstract at an international conference. But that was just the nature of my project. So I'm not sure if U of T thinks that is "productive".
Just my two cents. Not sure if anyone else can comment?