I think the problem is that your average layman might have heard of the WTF (because of the Olympics, and because Kukkiwon-style schools often have WTF banners on the wall) but your average laymen usually hasn't heard of the Kukkiwon (often only people inside the art have heard of it). It's the classic problem that all writers (and dictionary publishers) have: do you call something by its technically correct name, or by the name that it's more likely to be recognized by? Does one want to be right, or does one want to be understood? Is the purpose of language to educate, or is it to communicate? As has been pointed out many times in these forums, there's really no such thing as "WTF-style" per se, and yet often that's the name it's most often recognized by. Personally, I tend to gauge my audience and use whichever term that I think will be most likely understood.