Does your institution accept Passport Cards as a Primary form of ID? If not, can you please tell me why?

We do. I would opine it's a better primary ID than most, if not all DL's.

Yes we do. We accept regular passports as primary. Passport cards are obtained through the same rigorous process as regular passports. They just are in card form and are not good for air or sea travel.

Yup, we consider it a primary form of ID