If I may, I would like to toss in an opinion which I've been wrestling with for some time. I don't think instruments matter at all unless we want to distinguish "traditional folk" from "folk" itself. Seems to me that more important with age is the question of outlook. What you are calling "singer-songwriter" stuff, if I understand you right, deals with transient emotions, almost always love or lust, depending on your personal definition of the two. It's therefore subjective. It caters to the young because the young feel such things very strongly. It's all about how "I feel." Folk music is for working class adults who have to put food on the table and worry about larger things. Folk music describes the world out there; it's objective. It's not always pleasant, and does not always end happily, but it's real, and hands down lessons to those of the next generation who listen to it and are socialized by it. It's also more demanding musically, because it isn't all different combinations of 1-4-5 chord progressions.

Thanks; I'll be still now.

Chicken Charlie