Why are there only 3 Chess Piece Pokemon?

I just recently got into Pokemon again for the first time since I was a child and insantly fell in love with Pawniard, Bisharp and Kingambit.

I am genuinely shocked they never did the rest of the Chess Pieces as Pokemon. Imagine a real life Chess Set with these Pokemon as the pieces.The two color teams are even there wirh Shinies, what a missed opportunity!