"If any of us were saying that singers should be discouraged from singing those songs, your comment might have some point."
That has been said here and has been a constant complaint throughout my half century in the revival - from some quarters anyway..
"why should their political/social opinions have to be placed before the public during the performing or listening experience."
Whatever the expectancy of the audiences, the choice of material has to be the performers', his/her job is, as far as I'm concerned, to have done enough preparatory work to give a presentable performance and to have understood and been in touch with the song to pass it on to the listeners.
If the song falls flat because a singer only feels he/she "should" sing it, then that's reprehensible, but that can apply to any type of song. Is it a problem - some of the most passionate singing I've ever hears was on the Aldermaston Marches, or during the miner's strike, or at the anti-Vietnam War concerts - likewise, one of the most electric audience responses I ever witnessed was at the N.F.T. screening of 'The Killing Fields' closely followed by the premier of 'Under Fire'.
"Entertainment" is an odd word; I'm entertained by John Grisham and Val MacDairmid, but I'm also entertained by Steinbeck and Hardy. I was highly entertained by 'The Hobbit' over Christmas, and I expect to be thoroughly gob-smacked by 'Mia Maxima Culpa' and 'No' next week.
I get as much pleasure learning the songs by lifting the corner to see what they bring with them as I do singing and listening to them.
You do the best you can in passing the songs over, but what is passed over to an audience is (hopefully) what I, or any other singer feels they want to pass over - the choice is theirs/ours.
Jim Carroll