I have no problem with the 1954 definition myself, actually. More than likely this is because I've never felt affected by having my material defined.
I do a lot of Irish, English and Scottish traditional fare, and depending on who I'm playing with, I switch to Blues and to that newer sub-group commonly referred to as 'Contemporary Folk'.
I agree that the Wiki fails miserably towards the end of the article, but if I can put the 'Blues' genre into a box, 'Traditional' into another, and so on, I should then have no problem putting 'Folk' into its respective 'box'.
If someone says to me, though, that such-and-such a song isn't 'Folk', I'll probably agree... if it doesn't fit the definition; it wont affect my relationship with the song, however, nor stop me singing it
'Contemporary Folk' is a term of convenience, but at least it does differentiate between the old and the new.
Do I regard myself as a "folk singer?" Don asks. "I am usually called such. But the tightest I can pin it down is that I am a "singer-guitarist". I reserve the right to sing anything that catches my fancy."
... simple as that!
"... it is what you do, not the way that you do it..."