I don't know if pay-as-you-use works as a business model for something like Netflix. What they basically want to do is maintain a captive audience that will pay the fixed rate and keep their eyeballs on Netflix content. You're paying to get into their walled garden.

With pay-as-you-use, market pressure will drive prices down to the marginal cost of production (which is approximately 0 for digital content), because now the different streaming services are competing over every individual moment of your attention.