Panthers have a reputation for being loners and being sneaky/sly/pouncey. That's black-ish.
Chipmunks and squirrels don't have a reputation for spreading disease like rats do. They also have a reputation for mostly eating nuts, they aren't seen as critters that eat out of your trash and mess up the stuff inside your house (even if they actually might).
I would say the vast majority of color pie choices are deliberate, but you have to approach it from understanding that how we perceive or culturally understand an animal's nature is different from how they actually are. Then understand that the color choices are based on our perceptions, and not the reality.
This doesn't take away from their white nature, it just adds black nature. There's a reason that a lot of the brutal authority figures in Magic dip into the combination of white and black.
