So how does the transaction fee increase? Who enforces a fee for it, and doesn't that have an affect on the perceived value? In a way the node is essentially charging you a surcharge for the transaction you want (right?) so he can be profitable whereas now he is profitable because he gets awarded newly created coins.
No one enforces a transaction fee, but a miner/pool doesn't have to include transactions without a fee in their blocks. So if you want faster confirmation, you include a higher fee. That way you are put in the first block possible.