I'm 50% with you there. I agree that the show must have a group of songs that should be played every evening throughout the tour. However, in my opinion the other songs can be changed from gig to gig without affecting the experience. I don't wanna go to a concert knowing exactly which songs are going to be performed, that's boring. At the end of the day 20 songs are 20 songs.
you don't have to know the setlist before going to the concert.
of course it's hard nowadays, but if you don't read forums, social networks etc... you can go to the gig without knowing anything
I did that in 2010 : 2 months without read Guy's forum or AMIT before going to the gig, because in 2001 MKnews provided setlists, and it's one of my big regrets in my DS/MK fan life : knowing the songs before the gig starts
2005 was easy because I went to one of early gigs in the tour (so it was something like one week without reading anything), but 2010 was harder because I went to a gig at the middle/end of the tour
okay, since 2010, you know songs that will be played, even if you live in a cavern