I have often mentioned to my wife how so many - especially Country/Western - songs today have a 'refrain' or 'hook' that has no lyrics but only a oooh oooh thing going on between choruses, so that there can be a lot of audience participation ...
Even on senior gigs, I look for songs where the audience can sing out the title or a lead line like "... keep away from Run Around Sue" or "...that's the Wonder, the Wonder of You..." and of course there's always the "whoa, whoa, whoa, and so good, so good, so good, " of "Sweet Caroline" etc. etc. ...

Also, I think what is missing from this conversation is the fact that in the 50s the Doo Wop songs had basically 4 chords and the upbeat Rock and Roll songs were basically 3 chord blues ... how is that so different from what is being played today?