Primarily, I'm referring to how these things are marketed, not at anybody in particulars' set list.
But even 50's music is becoming something that only a tiny handful in our audiences can even remember from their youth. I certainly don't remember any music from the 50's, it's about the early 60's and onwards that was the music of my childhood and youth. Sure wasn't any big band!
Now, don't get me wrong, I've not only listened to much big band muusic, but some of my first pro gigs (as a young teenager) were playing in bigbands on t'bone. But it wasn't the music from MY generation (talkin' 'bout my generation!). That was the Beatles, The Who, The Stones, Motown, Stax...
I honestly think, if THAT is the music that dominates arranger factory demos (and onwards to the 70's and 80's), you are going to see an upwelling in use.
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An arranger is just a tool. What matters is what you build with it..!