Responding to the initial post purely in terms of FOLK music...

Based on what I hear on the mainstream folk outlets, eg specialist folk shows across the BBC, and albums by a lot of successful and up-and-coming acts billed highly on the folk festivla bills, I think it sounds so different because the sound of folk has been professionalized.

There's perhaps an irony there. In that from the 50s to the early 70s, folk actually sold a lot of records, yet was a lot less commercial in its sound, a lot rougher around the edges. And healthily so.

The technology/studio time wasn't there to ensure every single note was absolutely polished to perfection (thankfully), with all the dynamics of the music squeezed out in order to sound as loud as the pop records of the day.

However, this state of affairs does mean that when a musician pops up who doesn't care about all that, someone not interested in making perfect, polished, sanitized pop-folk, it really stands out. I of course refer to the noble few fighting the good fight, namely: Stick in the Wheel, Amy Annelle, Alasdair Roberts, Mary Hampton, Sharron Krauss, Cath & Phil Tyler and one or two others....