Earlier quoted context omitted.
The fact that you can buy "overage insurance" is telling and shows that UBB isn't about capacity, but instead a new revenue stream. If there was a legitimate concern regarding bandwidth and infrastructure, insurance wouldn't be offered and there would be hard limits to usage.
Revenue == funds to build capacity. If everyone really wants to stream Netflix 24 hours a day, the capacity will be built but it isn't free. This is how every single element of the economy works.
Plus, if the ISPs really want usage based pricing, then they should do that instead of this arbitrary download cap stuff that is nothing about usage based pricing.