The difference, at least in my mind, is that M'Cheyne, Lord Byron, Blaise Pascal (and many other famous people who made a name for themselves before dying young) were of another era; they'd have been dead by then one way or another, anyway.
Roy Orbison was my parents' music, and he was a few years older than them. In my mind, he was already an "old man"--even though the musicians I liked are now older than him by a decade or two.
Once it dawned on me that the music of U2, Duran Duran, Madonna, etc. is older to me now than the music of Orbison, Elvis, or the Beatles was in the 1980s, I got a bit more of a "long look," I guess.