People get sad. Over-sad? I think so. Like when Antonio Puerta died. Obviously it was a tragedy for one to die so young, but just reading the thread on here set up when he died, the level of tragedy seemed to be elevated so far beyond that which you'd expect to be associated with the death of a "normal" person of the same age, it was unreasonable. And I realise that in some instances, famous people can have deep and meaningful effects on people's lives, but I don't think that this was one of those instances.
Maybe they simply allow for us to collect our mourning into one package where mourning for each death individually would be impractical? Returning to the example of Puerta, maybe people's sorrow was not just for him in particular but merely representative of their sorrow for everyone, heard and unheard of, who had died in their early 20s? In a subconscious way, for the most part. DiScus?