Does anyone know why much Polish food is stuffed? are there historical reasons for this?
Hmm, yes, interesting issue. I don`t know right away, have to think a little. E..g, stuffed baby pig. They put various ingredients into it: kasha (finely ground barely), bacon, offal. See the recipe with pics by a Pole from the RSA:
wedlinydomowe.pl/grillowanie-i-pieczenie/piekarnik/1721-prosiak-nadziewany-kasza-daruje-sobie-nazwe-po-staropolsku-flagowy-przepis-wiktora-z-johannesburga-rpa
The reason for stuffing: apart from meat, one should also eat some carbs.