I suppose this is why Maka Dai Dai Shogi also has many demoting pieces, and makes the promoted state contageous. Demoting pieces are less useful as protectors, as near-equal trades can force those to demote by promoting in the initiating capture. Even if that is a demotion itself. You either gain the captured piece for the price of the demotion (which would always be better than the loss of the capturing piece due to recapture), or you trade with the recapturer's demotion as an additional bonus.
I suppose this is why Maka Dai Dai Shogi also has many demoting pieces, and makes the promoted state contageous. Demoting pieces are less useful as protectors, as near-equal trades can force those to demote by promoting in the initiating capture. Even if that is a demotion itself. You either gain the captured piece for the price of the demotion (which would always be better than the loss of the capturing piece due to recapture), or you trade with the recapturer's demotion as an additional bonus.
This tips the balance in favor of the attacker.