It displays an ignorance of traditional singing which I would have hoped we've grown out of - apparently not."
in my opinion the most important thing about singing any siong whether it be traditional or composed, is how the song is sung, tradtional singing is the same as any other genre of singing, to understand style it is necesary to have listened and absorbed the style.
   those revival singers such as Bert Lloyd who advocated singing with a smile on the face, were making it up as they went along,and were not basing their philosophy of singing on anything that was based on traditional singing styles, nearly all the traditional singers I have come across sang naturally,without ridiculous affectations such as singing with a smile and wiggling the backside.
here is harry cox singing without a smile and not wiggling his backside.http://www.youtube.com/watch?v=YsxG06FMA-Y to paraphrase mr punch "thats the way to do it".
in the case of BERT, I do not think it was ignorance, but more a determination to steer the uk folk revival in a certain direction, as for frankie armstrong and her shouting techniques, that was not based on traditional singing either.