As anyone who has been involved with Fantasy, Role Playing, and general geekiness will be able to tell you.. there is a long history of incestuousness between Hard Rock/Heavy Metal bands and the various realms of secondary creation. Led Zeppelin arguably was one of the earliest, with repeated references to Tolkien's work begging to appear on their 2nd album. But it wasn't until the space/prog rock period that the idea of a Concept album became possible.
Band's such as RUSH and King Crimson produced multi-part epic songs detailing entire story-lines based on secondary worlds. It's my suspicion that a RUSH song may have been the inspiration for The Sword of Shannara. Hawkwind collaborated repeatedly with Michael Moorcock. This sort of thing never really has gone away, it mutated maybe, but even bands like Metallica and Megadeth have songs which directly reference the words of H.P. Lovecraft. It has metastasized into bands such as Blind Guardian who create entire albums based around fantasy concepts.
Many of these albums though came from groups who never tried to hide these aspects, they were there from the very beginning. Worn proudly on their sleeves, be they J.C. Penny front pocket shirts or Denim jackets with the sleeves torn off. But occasionally you get a group which you think would do this sort of thing regularly, and instead what you get is stadium jock rock ala Ac/Dc. A Good example of this is KISS. Despite the make up and glam rock aspect of the band, their music for the most part deals more with partying and sex than it does with elves and adventures.
The exception being their 1981 album "Music from (The Elder)". The band does it's best to ignore the album. Which is a shame. It's a great experiment by a band which doesn't really challenge itself that much. But as with any unexpected experimentation this did not go over really well with the band's fans. Perhaps even less well than their brief experiment with ditching the Glam Rock makeup and costumes. People like KISS, but they like KISS to be KISS.
But "Music from (The Elder)" is a great fantasy album. It features lyrics written by Lou Reed, advanced vocalizations by Ace Freely, Faux Gregorian chants, extensive use of synthesizers and a continue story from beginning to end. It details the story of the selection and education of a young boy by a group of mystical elders so that he can confront the villainous Mr. Blackwell. It cries out for a sequel. Where does the boy go afterwords?
It's apparently the subject of a new crowd-sourced independent film which is in the early stages of being made. Described as 'The Road meets Excalibur'. I wish them luck on it. Films such as 'The Hunt for Gollum' illustrate that you don't need huge budgets to get high quality Fantasy films made.