I got here by googling "rock and roll hymns." Although you make many good points which prove definitively that some attempts at rocking classic hymns fall flat. I am at this moment listening to Paul Baloche's version of "All Hail the Power of Jesus' Name" I grew up singing this hymn. I have always loved it and this new version blows me away. You see, I'm 64 and I was also brought up with Rock and Roll. This Fall our church choir did "Awesome God" (in a choral arrangement) and it went over quite well. Tomorrow evening we will preform a Christmas Piece arranged by the Suwanee project in latin. I am also involved in a little ad hoc group working on a mass sing-in of "He Reigns." I write this to indicate that my musical taste are broad and varied and I take my gems where I find them. Have you listened to any of the reggae/ska versions of "By the Waters of Babylon?" They sound inspired to me and reflect that similarity of the experience of the Hebrews in Egypt and the African in America that is sometimes called "soul."
For me it all depends on the theological soundness of the lyric (some leeway is permitted, after all it is a song not a sermon.) and the prosody. The tune, rhythm, and mood must suit the theme and the lyric well
I would like to throw in a cautionary footnote that in times past graphic description of evil was permitted if it was clearly intended as a cautionary. So maybe "Highway to Hell?" or "Momma Told Me Not to Come" (just kidding.)
Wow - talk about resurrection from the dead of an old thread.
The pop music of 150 years ago wasn't all good, and sometimes it doesn't do any harm to re-do a hymn, especially of the new feel brings a fresh feel and isn't just twee. I know 3 or 4 versions of Be Thou My Vision that range from slow ballad through African beat to rock, all of which work well. Some hymns benefit from a reggae beat, livening up and injecting humour into a dry, cliched tune.
There's no reason on earth than they can't be adapted or changed provided it's done well.