The first thing to cut is supplements that people watch once and never want to watch again.
So you're saying that it's these different "extras" that are holding back many Blu-ray releases? This is like a serious question. Drop the extras and the floodgates will be open?
I don't see any connection with extras vs price vs releasing schedule. If you want "just a film", there are many streaming/DL/etc options and several HD channels. One of the main points with physical media is that different extras are included on the disc. I see no reason why we should go back in time with bare bones releases with high prices. Blu-ray disc holds 25-50gb and for a reason.
It's interesting how people see these extras. For many they're more like PR or just "something" that is thrown to the disc. Some even are annoyed that they're on the disc, even when they don't obviously have to watch them. For many they're a great way to learn history and learn about the film, filmmakers and their craft, etc. I mean many of these people are actually film historians and scholars, or relatives/close friends/co-workers of the director/actor etc. It's also interesting if some people feel that you can't "trust" them or that they're proving us just nonsense information.
For me the best "extras" are recording valuable film history for the future generations. It's actually a bit sad that some filmmakers or actors refuse to give any interviews or audio commentaries for the extras. I do understand some of the reasons why (especially in today's world, where media is often out of control), but still.