Why did the rise of Jukebox Musicals happen in the 90's?

I slightly paraphrased the offensive part of your post, but in full: "WWRY is unmitigated garbage on every level and is a sad indictment of how far we've fallen as a society."

You may not have meant the implication that people who like WWRY are somehow examples of how terrible you seem to think society is, or at least their taste in theatre is, but it's there.  You're entitled to dislike the show of course, but there was absolutely no need to make it a wider comment about people in general and I hope you can see how it can be read in a certain way that doesn't reflect well.  It's how I read the words you wrote - I'm just telling you what I took from your words, I can't get inside your head to know what you meant so I can only go by what I see on the thread.

I was also making a more general comment about some people's attitude to jukebox musicals in general, not specifically directed at you, so it's interesting that you jumped straight on the defensive, which to me suggests you (at least now if not before) realise your words might be read in a way that might cause a degree of offence.  It doesn't matter, it's just phraseology and the extent to which care is taken over word choice, I'm simply explaining why I personally (and it's just my opinion after all) had a problem with the phrasing used.  The comment about people in general in relation to jukebox musical snobbery stands though.

Revues, arising in the early part of the last century usually had original scores so were very different. In fact they often had a house composer, Irving Berlin for the Music Box revues, Gershwin for the George White's Scandals etc. The songs often became hits only because they were written for these shows.

It's really only in the seventies when the revue started to become more of a compilation of existing songs.