Strike my first post, I had the wrong end of the stick (songwriter's angle, not performer's). Except - the performer can choose his/her material to be educational or not.

Note that I don't say "political", but "educational", for the very reason that emjay above mentions (make them think, don't tell them what to think).

But the performer's first job is indeed to entertain, if only to retain the audience's interest and ensure he/she can have another gig. Everything beyond that is a calculated risk. Does the audience want to be "made to think"? One should be sensitive enough to their audience to decide sensibly. If they get it wrong, they only have themselves to blame.