I think there is short-term and long-term gratification playing a role here.
While it might be fun to get deleted by nunchuks once or twice, or even pwn others, I feel like it will get too old too quick solely because of its immense power. It's one of the first things you notice in the game once you play 5-10 matches.
The moment they spawn, same with the Shovel (these two weapons are hot- topics, this thread be the proof), anyone who knows what it is will make it their goal to get it. In my experience this doesn't happen with other weapons and that is saying something.
They have disadvantages, they can be counter-played (not always, as nunchuks, for example, often don't care about your drop-kicks), but the reward they give compared to the other weapons is undoubtedly much bigger.
I don't think the spawn rate for it is different from the other weapons. I see them every game together with the Shovel. They are just better weapons that make other weapons more or less obsolete.
Nerf often carries a negative connotation, same as buff often carries a positive one, and the best generalistic term for this is balance improvement. It doesn't have to be something awful; the game will retain its core design and character; the weapon still can be fun.
There can be many ways to go about it such as increasing self-KO chance, increasing stamina consumption or even locking it behind a spectator-owned throwable. I believe the devs can come up with something epic if they ever decide to tinker with it.
As it stands now, with the current situation in the game, I share the sentiment that Nunchuks and Shovel are busted.