Netflix's letter also said that in the US, the ad plan had greater total average revenue per member, which includes revenue from subscription fees and ads, than the $15.49/month Standard plan.
There you have it folks. Your eyeballs are worth more than $8.50/mo -- no wonder they're so hungry to get people to get used to ads. If they can get you to crack the door, they can slowly raise prices and also get that sweet sweet ad revenue.