While I get what you are saying, the difference in quality between Blu-Ray and Netflix/OtherStreamingServices[tm] is quite astounding. I completely agree that Streaming is good enough for most purposes, but if you want to watch a high quality picture on a top quality TV, then the streaming services don't yet cut it. That is a reason to (sometimes) collect physical media.
But the amount of films I'd care enough to have on physical media is severely limited. When Sony fought tooth and nail against HD-DVD to make Blu-Ray the "Standard" optical HD-format, I expect they thought they'd be able to milk that cow a bit longer.