The majority of people are probably also only using that e-mail to have somewhere for their Netflix receipts to go.
Email is obviously really important, but the cost of running Netflix is extremely different to running an email service and I would take that into account with the pricing.
But I think Netflix is extremely cheap/good value if you enjoy the content.
In my opinion, the fact that people would pay more for Netflix than their email provider is kinda crazy, when you think about their relative importance.