Yeah but the public's memory's are fickle. Only die-hard fans would research things like setlists. Casual Bowie fans wouldn't ever do that. This is how they would get their info:

DJ: And that was Modern Love by David Bowie - he plays GM Place on January 24th. There's still good seats left. Get 'em while they're hot!

Casual Bowie fan (who probably only owns Best Of Bowie or Let's Dance): "Oh Bowie's playing here! Cool! And he's playing the hits! Right on, let's go and see him.

I mean why else do you think radio jumped on the tour after tickets had went on sale in late September and then all of a sudden in early November, CC started pushing back almost all of the concert bowl configurations in arenas right after radio had done their thing?

Btw, after the Vancouver show, I heard a few people talking about how disappointed they were that he didn't play Modern Love or Let's Dance at the show....

...don't tell god your plans...