A Bishop would be delightful in Xiang Qi, wouldn't it?
However, if each side has 20 pieces, the B merely has to wait a bit longer
for the board to empty out and make it strong. The Knight's advantage in
the opening would last a bit longer, making it overall a bit stronger, but
still worrisome to give up B for N...
Consider the game of 'Weak!' in this context.