I don't think it's such a terrible idea. Better to hang out around the boards and read about real people who are going through real stuff than to get some misguided information elsewhere. I can completely understand why others would think it's offensive.

I guess before I can really make a judgement I would have to ask what your instructor wants you to get out of joining on online community. If it's to to read and ask questions instead of going to Wikipedia or something, lol... I would say that's great. If it's for other purposes, then not great. It really depends. I don't think there is anything better or wrong with learning about depression or any other illness than from someone who is going through it-- as long as you go about it in the right way and the participants are okay with it. In my opinion, it's about stating your purpose in a more specific manner. I guess I am a bit biased being a student of psychology and and a victim of it as well, lol.