There have been enough of them now so that journalists and editors (not the sharpest tools in the box, frankly) know what they are, and how to cover them and which stenographer-to-power to “report” the fun.
There haven’t been enough of them yet for them to smell of Stale News. It’s cheap and easy novelty. Photo of a pretty young thing dressed as this or that and voila, half of page 7 put to bed by noon.
There haven’t been enough for the organisers and punters to be bored.
There haven’t been enough of them yet for the police to have quite got their plays sorted yet (perhaps). [Though they played a blinder at Manchester Airport a week back…]