I confess your reasoning seems a little strenuous to me. It's not realistic to expect everyone to feel exactly the same about every single person who dies; nor is it humane to expect everyone to feel nothing about anyone who dies. I'm likely to care more about the death of someone I know and love than about the death of someone I know; more about the death of someone I know than about the death of someone I merely know of; more about the death of someone I know of than the death of someone I've never heard of; and so on. And of course the circumstances of those deaths are relevant as well; each death is going to arouse a different complex set of responses based on the age, lifestyle, personality, and family situation of the decedent.
I admit I was surprised that I had any emotional reaction at all to Ledger's unexpected death, since my only knowledge of him was through his films. But there was a response there, and I suspect it was because it was an untimely death coupled with the knowledge that he was talented, that he had a child, and that he didn't seem to live like, say, Chris Farley.
Since in this century so much of what we know of the world is vicarious, it's probably unrealistic to expect people to be able to divorce their emotions entirely from the people who engineer that vicariousness.
I will agree, however, that the media circus is grotesque, but then my disgust at that is driven in part by the same feelings that made me respond to the news of Ledger's death (and also in part, however, by the conviction that all those reporters ought to be in, say, Kenya instead).