Suit evolution is quite an interesting topic. The first known card decks were usually made of several hundreds of cards and were not standardized, some didn't even have suits. Symbols, images and shapes varied greatly as they were usually hand painted. This European suits are offshoots of Islamic suits. Most likely, each of these suit styles was an attempt to standardize some game or production at different historical points in time and through the interpretation by entirely different artists. The common theory for French abstraction is that they are much simpler symbols which are faster and easier to reproduce in large quantities. Particularly easy to engrave on the first woodwork prints for mass production.

I have no idea, but it looks like they would be much easier to paint with brushes. Or maybe it's to simplify printing with a press; simple shapes, one color each. Just wondering aloud.

Cheaper to print in bulk