"Apologist"? Really? An interesting thought.
I think one might ask on whether notated, arranged classical works for formal public performance which draw on folk tunes are a continuation of the tradition or a high-art development parallel with the tradition. There is a perceptible difference in spirit between, say, When I was Bachelor sung from memory in a pub with dirty-minded choruses and the same song arranged and accompanied by Benjamin Britten and sung by Peter Pears in front of a decorous audience.
Worth remarking that Britten's arrangement now sounds dated, as, to my ears anyway, does Grainger.
The tradition does of course draw on classical or art sources. Obvious thing is Michael Turner's Waltz which started life as a fragment of a Mozart German Dance.