Netflix is famous for their originals and their income purely depends on the subscribers, they anyhow needs to increase the subscribers base, they did try to make their service costly and lost many of subscribers recently, since india has more users compared to other countries who uses internet on mobile (thanks to jio and other service providers who made it happen) they have targetted for mobile users to increase the revenue. So i think they are doing pilot testing currently by introducing the mobile/tablet SD plan.
Note - Personally to me the quality of AQ and PQ of netflix for HD and UltraHD cannot be compared with other online apps.