Not much to say that hasn't already been sad. The world is a little less funny because of his death. While Robin's death shines a light on this issue for a few moments, people will have forgotten all about mental illness by next week, and will be onto what body part one of the Kardashian's is showing on the beach.
Depression hits people of all ages, genders, races, and religions. Some due to a terrible effect of their selfless service to the protection of others, and in some cases a very genetic issue. I have struggled with depression my entire life, as have my siblings, father, and grandfather. Most of society would prefer that people not talk about their depression, those with it can be discriminated against (in certain professions), and getting help can be very expensive as insurance limits what they will cover in terms of treatment. For me, I wont speak for others, the support of friends and family have been crucial to me finding my way out of the dark times I've had. When people feel that they can't openly share what they are going through and ask for help, it hinders their ability to overcome the darkness.
So I'm glad people are talking about it, as they did after many other celebrity deaths in the past, but until we as a society make openly dealing with depression okay, this issue will continue to stay in the closet for the majority of the population.