First and Foremost: Because Buddy's originals are associated with the innocence of the '50s, this is strongly enforced.
Germans Love David Hasselhoff: He was particularly popular in Britain, partly because he toured there when other contemporary American stars like Elvis never did. Notably the British press always had the Crickets pose with cricket bats for photos, even though their name was a reference to the insect rather than the sport.
Harsher in Hindsight: When Waylon Jennings gave up his seat on the flight, Buddy jokingly told him, "I hope your bus freezes over!" (the heating on the bus was broken). Jennings replied, "I hope your plane crashes!" Naturally, this haunted him for a long time.
Memetic Mutation: Buddy's glasses. He needed them, but Elton John didn't. He started wearing them as a tribute to Buddy. John Lennon also to some extent.
Replacement Scrappy: The Fireballs, Norman Petty's early '60s house band, who were used to overdub the demo tapes Holly left behind.
Tear Jerker: His wife was pregnant when he died, and she ended up miscarrying.
They Changed It, Now It Sucks: Hardcore fans hated the '60s overdubs. All of the undubbed originals were eventually released.