Being of an age where I recall my earliest exposure to the great songs and ballads of tradition as recordings by A.L.Lloyd and Ewan MaColl, I was exposed to unaccompanied songs quite a while ago. And I find more and more that I am tending to prefer to sing more songs with neither my guitar or concertina. A few of the reasons include the freedom one gets by not being dependant on the limitations of an instrument. The voice can do things that no machine can and may be better used without the limitations of keys, modes, tempos, etc. Like a previous respondant, I am also really unable to concentrate on complex singing and playing at the same time. I have found, however, that many audiences get confused by unaccompanied singing. But with enough exposure they too can be trained. A line from the introduction to the Penguin Book of English Folk Songs quotes a Dorset man's comments of a professional singer of folk song, "Of course, its nice for him to have the piano when he's singing, but it does make it very awkward for the listener."