Concept Albums - Form of Greater Art

Speaking of Ulver,I almost for that Nattens Madrigal is also a concept album and is my favourite from them but The Marriage Of Heaven & Hell is awesome also.
 
Darkside is great, and musically it is very cohesive, but lyrically I wouldn't qualify it as a concept album. What's the concept? Things that are important in life?

The Dark Side of the Moon is widely regarded as one of the quintessential rock concept albums. It isn't narratively conceptual, but thematically conceptual; primarily, its concept is insanity.

EDIT: and concept albums are by no means a "greater form of art." They have no special standing over "regular" albums.