Should I take OSAP (student loans) even if I can pay for my tuition?
I also considered doing this, though I didn't (more from sloth than anything else).

As I understand it, from other students in Ontario, you can pay back the entire OSAP loan in a lump sum at any time. Since the loan is interest free, a rational investor would take out the maximum amount allowed, put it in a risk free asset, and pay it back as late as possible, pocketing the interest. 

Now, interest rates are low right now, and OSAP needs a lot of paper work. Being in debt can also be stressful for some people. If you are sure that you won't need any OSAP money, then perhaps the $100 or so you'd make per year in interest is not worth your time.

Also, note that borrowing money now, and then paying it back early will often cause the provincial government to lower your future OSAP payments - since you clearly didn't need the whole amount.