To Eric the Red - I think that's to do with the same "hoverfly" rhythm I noted above.
Traditions exist due to folks being impressed by how their forebears did things (me)..? They loved thier unaccompanied folk songs, and it was basically the only form of entertainment available to them anyway (paraphrasing the late great Bob Copper)..?
George - I think it was Shirley Collins who I heard describe the E. trad style as being dispassionate, and old recordings (via BBC/EFDSS) I've heard back that up. Also, for a large part of English history being passionate about things was frowned upon - you know, stiff-upper-lip, etc.
Sue - England and many other countries are globalising/Americanising, and I'd hope that more American citizens themselves (for love of our world being multicultural) begin to question folkies from other nations singing in phoney American-accents, etc. (And, I think that relates to Melodeonboys "the new orthodoxy".)
Also, "art music" (another branch of early music) is basically classical composers getting hold of trad songs/tunes, I think.