I think there are issues about perception both within the medical community and within the wider population. When the generally used name for bipolar was manic depression then those without first hand experience of the condition would throw the term out and use it to describe anything and everything, including hissy fits, anger management issues and drunkeness. Now the term bipolar is more commonly used and various high profile names have shared their diagnosis and experiences so there is greater public awareness. Depressive illnesses haven't really had the same kind of makeover and have the image problem of being perceived as a low mood that we can think, eat, exercise, self help, our way out of and "just pull ourselves together".

Within the medical community, my experience is that depression is the poor relation. Perhaps because a major depression without psychosis and where harmful and suicidal behaviour is supressed or managed by the sufferer is a very "undemanding" condition. In this state, I hide myself away both physically and emotionally, I don't speak much and when I do I don't say much and certainly describing the full intensity of my symptoms would take more energy than I have at my disposal. So if I were a psych I'd be more likely to attend to the volatile, risky, "interesting" bipolar patient than the silent, placid, "boring" depressed patient.