The idea is that usage-based pricing doesn't make sense for customers because there is a hard limit on consumption simply based on the terrible state of last mile connections. Simply put, charging 2014 dollars for usage on a line with a capacity that was last relevant in 1985 is not motivated by actual capacity limitations, but a simple money grab.

(Not to mention that there are no inherent variable costs to transporting bits. Water needs to be purified, electricity is obviously usage priced - but you can be pushing bits forever once you have the hardware setup.)