The problem with accepting a metered rate is that it is completely divorced from the reality of the costs associated with providing your service. With utilities like gas, electricity, and water, there is a clear marginal cost for every additional unit you consume. This is not true for a unit of 'internet' from your ISP. Their operating costs are sunk and inflexible. Your next bit does not 'cost' them anything to send, so why should you pay for it as if it did?
How is it disconnected from the costs of providing the service? This could only be true if all connections were built to support the maximum possible bandwidth all costumers are theoretically capable of. Because otherwise, the price you're charged is a mix-calculation - it's the price that's required to deliver the promised number of bits during a given timeframe.
