Jukebox Musicals – cash cow or cash in?

Over recent years we’ve seen a growing number of what I refer to as jukebox musicals, i.e., writing a storyline and filling it up with hit songs that we’ve heard on the radio.  Sometimes they are about the relevant performer’s life story, e.g., Shout – Johnny O’Keefe, Dusty, Buddy, etc., others like Mama Mia, Priscilla, We will Rock merely use popular music for an unrelated story.  Is there a place for jukebox musicals  Do we need more of them?  Do they contribute to real musical theatre? Or are they just quick sure fire cash grabs for those who don’t have the inclination or the talent to write a completely new score?  What do you think?