I think the idea is to use Netflix streaming to supplement the DVD subscription. I don't understand what is wrong with having a huge archive of recent to very old content available instantly at the push of a button at no additional cost. New releases are far overrated. If you've waited long enough for the DVD to come out before you see the film, you can certainly wait a few more weeks until Netflix sends you the DVD. Granted you can't watch DVDs on a phone, but why in the hell would would anybody want to do that in the first place?
That's exactly how I use it. There are many old movies and TV shows I want to watch, and streaming fits the bill. I have lots of old shows queued up, and I will sit down and watch one when I want to watch TV but don't have time for a movie. I'm then free to use my DVD rentals for things not available on streaming.
And it makes my wife very happy that Quincy is available to stream.