There are certain figures regarded as immortal in rock music. To name a few:
Stevie Ray Vaughn
and the like. I don't necessarily agree with some inclusions (I'm not sold on Morrison and Cobain, for starters), but for all intents and purposes those are commonly known "immortals" in rock music. What holds these together? They're all dead. And this leads me to my first Immutable Law in Rock Music:
To be truly immortal in Rock Music, one must die.
Of course, this makes zero sense at first. If you're dead, how are you alive? You're no longer making music. But take a look. Posthumous careers for many of these careers have either overshadowed or recharged some careers. I'm going to pull a different example than some of the people I listed above to prove my point: Ian Curtis of Joy Division.
Joy Division were not really well known when Curtis died. They were on the rise, but not really at that point yet where they got it "good." And then, poof! Ian Curtis, gone from the world. And then everyone discovered "Love Will Tear Us Apart," and the landmark records Unknown Pleasures and Closer. Then, all of a sudden, Joy Division were kind of a big deal. This allowed New Order (the rest of Joy Division) to get a head start, and has furthermore led to reissues, reprintings, and box sets of Joy Division's work. If Ian Curtis had died, would Joy Division have been big? Sure. Would they have been as big as they are now had Ian Curtis died? Arguably, no. Ian Curtis' death casts a long shadow over the melancholia that permeates every Joy Division song. In light of his depression and epilepsy, Joy Division records and songs gain a whole backstory and a whole new meaning. Divorced from their meaning, the songs are quite obviously powerful, muscular, and constantly effecting, but with this meaning every Joy Division song becomes a tour de force that simply obliterates the listener when heard.
The context of death makes everything about the artist more striking, granting the band/artist an aura that is impossible to penetrate. To elaborate on the above example, Ian Curtis, on his dying day, watched a Herzog film, put on Iggy Pop's the Idiot, and then hung himself. Curtis has attained a sort of mysticism due to that. Marvin Gaye was shot by his father, John Lennon was assassinated, while Kurt Cobain and Jimi Hendrix died due to overdoses. They're all now seen with a sort of reverence, an air of the mystic thanks to their deaths.
Each person who has died in the midst of their career has, in a sense, gained a sort of "impenetrable fog" that protects them from any sort of heated criticism and guarantees them a favorable standing in the world of rock music. I'm not saying it's undeserved. Lennon obviously deserves the "impenetrable fog"; his work with the Beatles, Plastic Ono Band and Imagine are all stone-cold classics and monoliths in rock music, and as an activist his edge has been unmatched. But Walls and Bridges? Some Time In New York City? Neither record is much better than mediocre, in my humble opinion. But his death erased any sort of criticism that could be levied against him.
This is why I'm inclined to believe Paul McCartney often suffers in critic circles: he's still around, he's still pounding it out, but either because he's been oft considered as the "soft" Beatle or because of his long career which has led to a fair number of duds to go alongside his many, many studs, he's likely the least respected Beatle (though perhaps Ringo also is given this same title). Now of course, saying someone is the least-respected Beatle is saying the fourth-most respected artist of all time, but that's neither here nor there. John Lennon has two (to three, depending on your level of scathing) duds to go alongside his studs. Granted, it's folly to extrapolate a career and look at sample sizes to examine careers of rock musicians, but it should be duly noted.
I'm also not ragging against John Lennon. Let me make that clear. John Lennon is the fucking man. I observe his birthday and his dying day every year. I don't take the day off, but for that whole day, John Lennon, everything he did and everything he stood for is always on my mind. But his death has granted him a place in the hallowed hall of rock immortals, perhaps given a slightly easier screening process than others. As have countless others, for better or for worse.
If you look at the ripples caused by a musician's death, the effect is pretty obvious. At least nowadays, the artist in question is rewarded with many, many posthumous awards and accolades. George Harrison was inducted into the Rock and Roll Hall of Fame shortly after his death. Ray Charles won a whopping eight Grammies from his record, Genius Loves Company, which was released two months after his death. Johnny Cash's American IV won a few CMA's and his rendition of "Hurt" absolutely slayed everyone and reaped some rewards soon after he passed (myself included...but his rendition of "Hurt" is great regardless of the circumstances).
The general rule? In rock music, sometimes it's better to die than to live. It doesn't make any sense, really, but it's true. It's truly a peculiar phenomenon. But it's observable. To refuse to acknowledge its existence is shortsighted. It's not talked about a lot...but it's there. Sort of like a dirty little secret. It's also something that should never be wished on someone. Death for the profit of afterlife. Perhaps it is the manifestation of "what could have been?" had they continued to be around; continued to be the great musicians they were.
Key, though, is to enjoy the careers that these immortals have brought us before their dying breath. In this sense, each album is worth more because there are less albums around. So it's therefore to critical to enjoy each landmark work each immortal brings us, to listen and bask in its eternal glory.