As there is a rob system i think there should be a trade system as well
I think that there should be an pve are where all villages gather and trade and sell stuff buyed costmetics could be banned from trading and dropped items would have a greater value to the game that way
to give an example, a strong shinobi can sell their weak stuff a shinobi actually needs it that way currency and items would have a greater value and that would add much more stuff to the games economy part