"in all my years working in folk clubs, certainly in the last ten or so I've never heard anyone sing "tedious, introspective, teenage angst ditties."

Well I bloody have. You obviously haven't been to enough clubs. Nowadays you can do an NVQ in Boring the Arse off a Folk Club Audience 101. Mind you for the for the higher grades you must attempt three slip jigs, a hornpipe and the Ballad of Tam Linn, and forget the tunes and most of the words.