I've experienced very little "mean-spirited, often cruel" formal criticism (can only think of two exponents of this nowadays) - plenty of snydeswiping, but that's different and it happens everywhere.
Good, positive, analytical criticism (as distinct from the anodyne first-name sycophancy that passes for criticism nowadays) should be the sounding-board against which we measure everything we do in public. The fact that this is what the folk scene lacks has much to do with the pap we are often fed in the name of folk.
As the Cap'n suggests - raise the standards of criticism and the level of performance will follow.
I often wonder, are folkies the only group of performers who almost universally consider themselves above criticism and who believe that standards have no place in their chosen field of performance? It seems to me that if you stick your bum out of the window you are inviting somebody to paint a face on it.
Jim Carroll