Point was these are not new. And the need for transaction fees is solved by reducing the movement of sub coin amounts to the “network cost” of moving a coin and by having a real PUT cost to have a wallet and maintain it.
When MD updates are going to cost PUT balance then the maintenance of the wallet (creation, adding/removing coins is going to become the inherent transaction fee. While there is no cost to moving a coin there will be at least one or 2 PUT costs to add/remove the coins to/from the wallet. The same for part coin balance.
It is a small cost for ordinary usage and would typically be tons less than anything around the place it does add up for any attack using small amounts. And limiting part coin balances to created wallet data structures make attacks much more costly.