We're entering an era in rock history where "live fast, die young, leave a beautiful corpse" will soon be replaced with "live long, die slow, leave a beautiful album."
The last two years have seen several high-profile last albums from dying artists, and I suspect more will be on the way as artists from the golden age of Rock confront their mortality. Joey Ramone's final effort, 2002's "Don't Worry About Me" and Warren Zevon's August 2003 release "The Wind" were both recorded as the artists raced the clock against cancer, and Johnny Cash released three albums between being diagnosed with and dying of Parkinsons-related ailments.
There is something novel about music written by dying songwriters. Even if the material has little to do with death on the face of it, their condition, as long as the listener knows about it, inevitably colors the listening experience. It's part of a larger package of "performativity" issues that pointy-headed academics (like me, sometimes) talk about, and which boil down for our purposes to the relationship between a fan and the musician they venerate, and how that relationship works in the fan's mind.
Part of popular music's appeal has always been in the persona the performer creates. From the on-the-spot character plays and dying-children ballads of Vaudeville and music halls to Jimmie Rodgers as "The Singing Brakeman," Johnny Cash as "The Man in Black" to Curt Cobain as "Tortured Genius," how an artist presents themself is tightly bound up with the music itself. Without the personas, the music would still stand up, but the songs are richer for them.
Paradoxically, in light of the importance of image, rock has always thrived on asserting its "authenticity." Long before the first rapper kept it real, rock and roll musicians were downplaying artifice, theatricality, and forethought in favor of instinct, spontaneity, and honesty. Of course, to present yourself as honest can take a lot of planning, acting, and hard work (viz. Jimi Hendrix, Bob Dylan), but that's beside the point. The point is, popular music is often assumed to be (or presented as) an unedited communique' from the singer's heart to you. Indeed many artists enjoy the interplay between their "real" selves and the characters they create, and this interplay only works if the perception remains intact that the artist has a "real" side visible to the fan.