I mean, there were goths/emo kids around the time Poppy Playtime is based in as well. Plus, if you really think about it, it's like a little cherry on top to complete the Critter Crew.

DogDay: the Leader

CatNap: the Sleepy one

Kickin' Chicken: the Cool Kid

Bobby BearHug: the Loving Heart

CraftyCorn: the Artist

Bubba Bubbaphant: the Brains

Picky Piggy: the Stomach

Hoppy Hopscotch: the Athlete

If the new critter is what everyone thinks they are, then it adds a nice bit of equality and evens out the crew. Also, if I were a toy designer of the time the game was based in I'd do the same, so really it's like they're thinking the way people of that time frame would think as well. Adding realism to the game.