The reason that so many of the ancient story-song ballads were written in rhyme and set to music in the first place was to facilitate memorization. Shared folk culture, or "lore," survived only because the bards or troubadors within a society held the words within their minds and were able to pass the material on down, generation after generation.

It boggles the mind to realize that even tremendously lengthy epic poems (like the Iliad and the Odyssey) survive to this day only because successive generations of pre-literate balladeers were able to commit them to memory.

Of course, in today's world, we all have way too much stuff cluttering up our brains to even consider learning such humonguous texts verbatim. Also, precious few of us seem to be in a position to make a full-time profession out of preserving and performing traditional song.

I agree with MTed ~ live and let live ~ but while I encourage tolerance of singers' rights to use notes or not, I do think we should all repect and be conscious of the notion that learning and knowing songs is part of folk-music tradition and history, and that visibly reading either words or music, while entirely normal for classical performance, choir singing, etc., can justifiably be seen as inappropriate in many folk-music contexts.