Where did this idea originate that the audience can demand what the performer's repertoire is to be?

Guest P.A. -- I find your "either-or" dichotomy much too limited. I perform music for money (not much money, generally), and I do it for the craic, which is to say, because I enjoy it. I do not sing 30-verse laments for the benefit of my own ego, nor do I sing PC or RC material. Neither do I perform "low-down shite".

As I've said in another thread, just because they pay you doesn't mean you're a prostitute. My band plays material we deem to be of quality. Many folks like it, others don't care. We don't do requests unless it happens to be something that's in our repertoire.

Any performer who lets himself be intimidated by drunken boors should find another gig. To thine own self be true!

Cheers,
Michael