They hand out the drugs because somebody wanted a cartoon about goats.
Mordecai fits the Pooka into the floor's political scheme: the Krakaren manufactures the drugs and the Pooka distribute them, and the Pooka are meant to represent The Plenty, a caprid race who look like goats. The party has never fought one, but Carl remembers that Elle McGib and Imani C have — Elle described them as goblin things that turn into giant goats when you fight them, and they were the ones dosing the mobs with the addictive vitamin shots.
Carl's reaction to learning that the drug-dealing goat men are a metaphor is to ask, incredulously, whether the entire floor is a bullshit political point. Mordecai says that is what it looks like.
Fuzzy goblin-like dealers who swell into giant goats when provoked.
The floor's drug distributors, and a caricature of the Plenty.