Improvisation is very much a state of mind; it moves in the moment aware of the organic uniqueness of all things and doesn't come with too much by way of preconception. It's also tolerant of a myriad possible outcomes. It's also a matter of dynamics and interaction / dialogue as well as striving for something as transcendently elusive as innovation. One might draw parallels between Improvisation and Sexual Intercourse (best not done in public?!) and conversation. Personally I'm always amazed there isn't more improv in folk music really; certainly it plays a large part in most things I do, even Traditional Songs & Ballads, the modality of which engender those sorts of freedoms & fluidities. Having grown up with Folk in the context of Free Improvisation / Psychedelic Rock / Jazz and diverse medieval / ethnic / experimental idioms, then I don't really have those sorts of distinctions, or expectations. However, as I'm sure I've said before, in a Folk Context I'm aware that Improv is a no-no, though in an Improv Context, audiences are more than happy to listen to a ballad or two...