It's entertainment for gawd's sake!
If the judges wanted a "serious" dance competition they should re-introduce "Come Dancing" and watch the viewing figures fall down to embarrassing numbers.
Personally I even find the current "perfection" of the celebrities a bit nauseating. Surely the whole point is to see non-pro-dancers having a go. I agree that iot is a fiasco if someone who's completely inept wins the competition, which nearly happened with that awful kid from eastenders, but the judging is now such that it can't happen. If the viewers want John to stay, he should stay, end of story. There's no way he can win the final, or even get that far (when it gets down to four, he has to be in the dance-off if the judges give him the lowest score, regardless what the viewers vote.) so why not keep a bit of entertainment until that day.
Craig should remember what he's being paid for... to appear on a show designed to entertain. If he wants to be a "serious" judge then he should stick to "proper" ballroom dancing contests, which aren't televised and are unlikely to be!