I think Cliff Burton and Randy Rhoads are overpraised musicians because they died young. Randy Rhoads was not an innovative player
A couple years ago, I started a thread titled something like, "Was Randy Rhoads Overrated?" My answer was yes, but even I think the bolded is a silly statement. Of course he was innovative.
But I do agree that both Rhoads and Burton are overrated a bit -- primarily because their bodies of recorded work as so minimal. With Burton, it's KEA, RTL and MOP, and with Rhoads, it's the two Ozzy albums and a couple Quiet Riot albums that were released only in Japan, and which very few people have heard and about which no one talks. Neither one of them has enough of a resume to be considered an all-time great.
As far as the main premise of the thread: Does an artist's popularity exceed my own subjective enjoyment of or reverence for that artist? If so, then the artist is overrated. Does my own subjective enjoyment of or reverence for an artist exceed the artist's popularity? If so, then the artist is underrated.
In that regard, artists/album that I consider overrated include The Doors, Guns n Roses, Bruce Springsteen, Power Windows, and virtually every pop star going back to 1970.
EDITED to be more coherent.