It seems to take quirky singer-songwriters an unusually long time to get into the Rock and Roll Hall of Fame. Tom Waits, Dr. John and Randy Newman only got their statues these past couple of years. Warren Zevon didn't have quite the success of those icons, but his best work ranks up there with anybody's.
Zevon has yet to even appear on a Hall of Fame ballot, even though his 2003 death finally made the public aware of his incredible genius. The Hall of Fame is pretty good at looking back and bringing in overlooked greats like him; it might take a few more years, but his time will come, too. They can probably even get Bruce Springsteen to deliver the speech.