"So I knocked it up in 10 minutes. "
Sorry Steve - shouldn't have done that - battle fatigue.
Basically, I don't disagree with much of what you wrote - I think it's a fair summary of what happens in many folks clubs.
What worries me is that if we can scribble our definitions off in ten minutes, why can't everybody?
I come to folk song from a number of directions, as do you.
I enjoy listening and singing, but I also believe it carries a load of important historical and social baggage with it.
I have to either make rational sense of both of them together or treat them as separate entities.
Up to now it's been no problem
The clubs I have been involved with basically featured traditional songs, but also encouraged the singing and writing of new ones.
I became hooked on ballads through listening to MacColl, who insisted that traditional singing would have no relevance if new songs weren't added to the repertoire.   
He probably wrote more contemporary songs than anyone on the scene, yet he was accused of being a purist ("finger-in-the-ear" was based on the way he performed).
Around a quarter of my own repertoire are songs that have been made during my lifetime.
My real concern is that the further you move away from the exiting definition without replacing it with another that we can all agree on and work with, the more chance we have of losing what we've got.   
I don't think I imagine the hostility I sense when these topics come up.
Again apologies
Jim Carroll