When I was a wee bit younger I followed bands that were known for their Improvisation and "synergy" with the crowd. Each of their live shows were very different from each other, I would see a group of shows by a band, maybe 8-12 shows in a row, and they were all very different, different sets, songs, and even instruments. Some call these kind of bands " Jam bands" and most of the time one song flows into another, into another. It is not odd to have 2-3 hours of non-stop music within these shows.
Bands like : Ozric Tentacles, String Cheese Incident, Rusted Root, Blues Traveler, Phish, The H.O.R.D.E. tour, and now even Tedeschi-Trucks and Bela Fleck and Gov't Mule.
If I would have seen a program, a song list, or any kind of choreographed structure, they would have lost my interest and following. If you have never seen a performance that captures the soul of everyone in that building, breathes in the emotion, and then hands it back to the crowd with a more connected performance, then you have not seen/heard real "live" music. This brand of Live music has a life of its own, and the real fans collect recordings (some bootlegged) of each show, and the shows that they've been a part of... well I dare you to talk to them about it.
When I hear the word "program", this is what I think: practiced, choreographed, sterile and lifeless. Binary music for all the ones and zeros. Please forgive, ...more judgements...
I might be wrong, but I think you are coming at this from the angle - " if a set list has more songs or compositions on it that I don't care for, then I don't want to go" ...
My perspective is this - " Why would I go to a show where the set list is a preprogrammed, robotic and rigid structure, that disallows Improv? Music that is Alive, is inherently improvisational."
Just different opinions, from different perspectives and different experiences.