Earlier in this thread, I quoted and emphasised a sentence written by Bren, my old friend and long ago fellow band member (no music stands). Now I feel the need to reiterate in people's minds whoever Tone or canalwheeler is when s/he writes:-

Isn't it all about whether you want to promote the song, or yourself? If you want to promote the song, then why haven't you learnt it? It is obviously worth it.If you want to promote yourself, does anyone else care?

Bingo! The nail is hit firmly on the head once again! If you love a song enough to want to sing it then learn it so that you can do it justice.

Now to counter the "classical musicians read the words & the dots, why not us." argument:-
An ex-work colleague of mine was a semi-pro member of one of the country's leading classical choirs much in demand to sing with symphony orchestras in studio and concert stage. She used to get me free tickets when the choir sang in Brighton. I once asked her if the choir really needed to hold their books in front of them when they sang. She was amazed at the question. "Of course, we don't! We need to know each piece inside out, back to front - we can sing them in our dreams. Holding the music in front of us is just a convention."
Some of the works that she was talking about were much more complex than the utterly wonderful lyrics and melodies that the tradition gives us.

The traditional singers that I was lucky enough to see and hear live and who inspired me to want to sing all those years ago - the likes of D. Stewart, J. Robertson, P. Tunney, J. Turiff, Blairgowrie Stewarts, G. Hall, W.Scott, F. Jordan etc. etc. - none of them read the words when they were performing. In fact, some of them struggled with basic literacy, but they were all consummate artists. Their standards gave the folk revival something to aspire to.

I have found it depressing reading the comments of the apologists for a shoddy ill-prepared approach that I have found in this thread.