"I might be able to slip a Traditional Ballad into a performance of Free-Improvisation or Experimental Ambient Electronica, one could never return the favour. I guess non-folk audiences are more open minded as regards musical possibility..."
It might be interesting to see how some so-called 'nu-folk' (I think) might evolve and tackle that?
Though I'm guessing your broadly on the button with non-devoted folk audiences v's devoted folk audiences. Folk - and perhaps English traditional music in particular - does indeed appear to exist in something of an hermetically sealed bubble?